diff --git a/wp-admin/customize.php b/wp-admin/customize.php
index e45254c74a..0a5350f54c 100644
--- a/wp-admin/customize.php
+++ b/wp-admin/customize.php
@@ -20,6 +20,31 @@ if ( ! current_user_can( 'customize' ) ) {
 	);
 }
 
+/**
+ * @global WP_Scripts           $wp_scripts
+ * @global WP_Customize_Manager $wp_customize
+ */
+global $wp_scripts, $wp_customize;
+
+if ( $wp_customize->changeset_post_id() ) {
+	if ( ! current_user_can( get_post_type_object( 'customize_changeset' )->cap->edit_post, $wp_customize->changeset_post_id() ) ) {
+		wp_die(
+			'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1>' .
+			'<p>' . __( 'Sorry, you are not allowed to edit this changeset.' ) . '</p>',
+			403
+		);
+	}
+	if ( in_array( get_post_status( $wp_customize->changeset_post_id() ), array( 'publish', 'trash' ), true ) ) {
+		wp_die(
+			'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1>' .
+			'<p>' . __( 'This changeset has already been published and cannot be further modified.' ) . '</p>' .
+			'<p><a href="' . esc_url( remove_query_arg( 'changeset_uuid' ) ) . '">' . __( 'Customize New Changes' ) . '</a></p>',
+			403
+		);
+	}
+}
+
+
 wp_reset_vars( array( 'url', 'return', 'autofocus' ) );
 if ( ! empty( $url ) ) {
 	$wp_customize->set_preview_url( wp_unslash( $url ) );
@@ -31,12 +56,6 @@ if ( ! empty( $autofocus ) && is_array( $autofocus ) ) {
 	$wp_customize->set_autofocus( wp_unslash( $autofocus ) );
 }
 
-/**
- * @global WP_Scripts           $wp_scripts
- * @global WP_Customize_Manager $wp_customize
- */
-global $wp_scripts, $wp_customize;
-
 $registered = $wp_scripts->registered;
 $wp_scripts = new WP_Scripts;
 $wp_scripts->registered = $registered;
@@ -115,7 +134,11 @@ do_action( 'customize_controls_print_scripts' );
 		<div id="customize-header-actions" class="wp-full-overlay-header">
 			<?php
 			$save_text = $wp_customize->is_theme_active() ? __( 'Save &amp; Publish' ) : __( 'Save &amp; Activate' );
-			submit_button( $save_text, 'primary save', 'save', false );
+			$save_attrs = array();
+			if ( ! current_user_can( get_post_type_object( 'customize_changeset' )->cap->publish_posts ) ) {
+				$save_attrs['style'] = 'display: none';
+			}
+			submit_button( $save_text, 'primary save', 'save', false, $save_attrs );
 			?>
 			<span class="spinner"></span>
 			<button type="button" class="customize-controls-preview-toggle">
diff --git a/wp-admin/js/customize-controls.js b/wp-admin/js/customize-controls.js
index 4410593a0b..db6403879e 100644
--- a/wp-admin/js/customize-controls.js
+++ b/wp-admin/js/customize-controls.js
@@ -22,26 +22,42 @@
 	 */
 	api.Setting = api.Value.extend({
 		initialize: function( id, value, options ) {
-			api.Value.prototype.initialize.call( this, value, options );
+			var setting = this;
+			api.Value.prototype.initialize.call( setting, value, options );
 
-			this.id = id;
-			this.transport = this.transport || 'refresh';
-			this._dirty = options.dirty || false;
-			this.notifications = new api.Values({ defaultConstructor: api.Notification });
+			setting.id = id;
+			setting.transport = setting.transport || 'refresh';
+			setting._dirty = options.dirty || false;
+			setting.notifications = new api.Values({ defaultConstructor: api.Notification });
 
 			// Whenever the setting's value changes, refresh the preview.
-			this.bind( this.preview );
+			setting.bind( setting.preview );
 		},
 
 		/**
 		 * Refresh the preview, respective of the setting's refresh policy.
+		 *
+		 * If the preview hasn't sent a keep-alive message and is likely
+		 * disconnected by having navigated to a non-allowed URL, then the
+		 * refresh transport will be forced when postMessage is the transport.
+		 * Note that postMessage does not throw an error when the recipient window
+		 * fails to match the origin window, so using try/catch around the
+		 * previewer.send() call to then fallback to refresh will not work.
+		 *
+		 * @since 3.4.0
 		 */
 		preview: function() {
-			switch ( this.transport ) {
-				case 'refresh':
-					return this.previewer.refresh();
-				case 'postMessage':
-					return this.previewer.send( 'setting', [ this.id, this() ] );
+			var setting = this, transport;
+			transport = setting.transport;
+
+			if ( 'postMessage' === transport && ! api.state( 'previewerAlive' ).get() ) {
+				transport = 'refresh';
+			}
+
+			if ( 'postMessage' === transport ) {
+				return setting.previewer.send( 'setting', [ setting.id, setting() ] );
+			} else if ( 'refresh' === transport ) {
+				return setting.previewer.refresh();
 			}
 		},
 
@@ -65,9 +81,166 @@
 	});
 
 	/**
-	 * Utility function namespace
+	 * Current change count.
+	 *
+	 * @since 4.7.0
+	 * @type {number}
+	 * @protected
 	 */
-	api.utils = {};
+	api._latestRevision = 0;
+
+	/**
+	 * Last revision that was saved.
+	 *
+	 * @since 4.7.0
+	 * @type {number}
+	 * @protected
+	 */
+	api._lastSavedRevision = 0;
+
+	/**
+	 * Latest revisions associated with the updated setting.
+	 *
+	 * @since 4.7.0
+	 * @type {object}
+	 * @protected
+	 */
+	api._latestSettingRevisions = {};
+
+	/*
+	 * Keep track of the revision associated with each updated setting so that
+	 * requestChangesetUpdate knows which dirty settings to include. Also, once
+	 * ready is triggered and all initial settings have been added, increment
+	 * revision for each newly-created initially-dirty setting so that it will
+	 * also be included in changeset update requests.
+	 */
+	api.bind( 'change', function incrementChangedSettingRevision( setting ) {
+		api._latestRevision += 1;
+		api._latestSettingRevisions[ setting.id ] = api._latestRevision;
+	} );
+	api.bind( 'ready', function() {
+		api.bind( 'add', function incrementCreatedSettingRevision( setting ) {
+			if ( setting._dirty ) {
+				api._latestRevision += 1;
+				api._latestSettingRevisions[ setting.id ] = api._latestRevision;
+			}
+		} );
+	} );
+
+	/**
+	 * Get the dirty setting values.
+	 *
+	 * @param {object} [options] Options.
+	 * @param {boolean} [options.unsaved=false] Whether only values not saved yet into a changeset will be returned (differential changes).
+	 * @returns {object} Dirty setting values.
+	 */
+	api.dirtyValues = function dirtyValues( options ) {
+		var values = {};
+		api.each( function( setting ) {
+			var settingRevision;
+
+			if ( ! setting._dirty ) {
+				return;
+			}
+
+			settingRevision = api._latestSettingRevisions[ setting.id ];
+
+			// Skip including settings that have already been included in the changeset, if only requesting unsaved.
+			if ( ( options && options.unsaved ) && ( _.isUndefined( settingRevision ) || settingRevision <= api._lastSavedRevision ) ) {
+				return;
+			}
+
+			values[ setting.id ] = setting.get();
+		} );
+		return values;
+	};
+
+	/**
+	 * Request updates to the changeset.
+	 *
+	 * @param {object} [changes] Mapping of setting IDs to setting params each normally including a value property, or mapping to null.
+	 *                           If not provided, then the changes will still be obtained from unsaved dirty settings.
+	 * @returns {jQuery.Promise}
+	 */
+	api.requestChangesetUpdate = function requestChangesetUpdate( changes ) {
+		var deferred, request, submittedChanges = {}, data;
+		deferred = new $.Deferred();
+
+		if ( changes ) {
+			_.extend( submittedChanges, changes );
+		}
+
+		// Ensure all revised settings (changes pending save) are also included, but not if marked for deletion in changes.
+		_.each( api.dirtyValues( { unsaved: true } ), function( dirtyValue, settingId ) {
+			if ( ! changes || null !== changes[ settingId ] ) {
+				submittedChanges[ settingId ] = _.extend(
+					{},
+					submittedChanges[ settingId ] || {},
+					{ value: dirtyValue }
+				);
+			}
+		} );
+
+		// Short-circuit when there are no pending changes.
+		if ( _.isEmpty( submittedChanges ) ) {
+			deferred.resolve( {} );
+			return deferred.promise();
+		}
+
+		// Make sure that publishing a changeset waits for all changeset update requests to complete.
+		api.state( 'processing' ).set( api.state( 'processing' ).get() + 1 );
+		deferred.always( function() {
+			api.state( 'processing' ).set( api.state( 'processing' ).get() - 1 );
+		} );
+
+		// Allow plugins to attach additional params to the settings.
+		api.trigger( 'changeset-save', submittedChanges );
+
+		// Ensure that if any plugins add data to save requests by extending query() that they get included here.
+		data = api.previewer.query( { excludeCustomizedSaved: true } );
+		delete data.customized; // Being sent in customize_changeset_data instead.
+		_.extend( data, {
+			nonce: api.settings.nonce.save,
+			customize_theme: api.settings.theme.stylesheet,
+			customize_changeset_data: JSON.stringify( submittedChanges )
+		} );
+
+		request = wp.ajax.post( 'customize_save', data );
+
+		request.done( function requestChangesetUpdateDone( data ) {
+			var savedChangesetValues = {};
+
+			// Ensure that all settings updated subsequently will be included in the next changeset update request.
+			api._lastSavedRevision = Math.max( api._latestRevision, api._lastSavedRevision );
+
+			api.state( 'changesetStatus' ).set( data.changeset_status );
+			deferred.resolve( data );
+			api.trigger( 'changeset-saved', data );
+
+			if ( data.setting_validities ) {
+				_.each( data.setting_validities, function( validity, settingId ) {
+					if ( true === validity && _.isObject( submittedChanges[ settingId ] ) && ! _.isUndefined( submittedChanges[ settingId ].value ) ) {
+						savedChangesetValues[ settingId ] = submittedChanges[ settingId ].value;
+					}
+				} );
+			}
+
+			api.previewer.send( 'changeset-saved', _.extend( {}, data, { saved_changeset_values: savedChangesetValues } ) );
+		} );
+		request.fail( function requestChangesetUpdateFail( data ) {
+			deferred.reject( data );
+			api.trigger( 'changeset-error', data );
+		} );
+		request.always( function( data ) {
+			if ( data.setting_validities ) {
+				api._handleSettingValidities( {
+					settingValidities: data.setting_validities
+				} );
+			}
+		} );
+
+		return deferred.promise();
+	};
 
 	/**
 	 * Watch all changes to Value properties, and bubble changes to parent Values instance
@@ -1215,6 +1388,57 @@
 			}
 		},
 
+		/**
+		 * Load theme preview.
+		 *
+		 * @since 4.7.0
+		 *
+		 * @param {string} themeId Theme ID.
+		 * @returns {jQuery.promise} Promise.
+		 */
+		loadThemePreview: function( themeId ) {
+			var deferred = $.Deferred(), onceProcessingComplete, overlay, urlParser;
+
+			urlParser = document.createElement( 'a' );
+			urlParser.href = location.href;
+			urlParser.search = $.param( _.extend(
+				api.utils.parseQueryString( urlParser.search.substr( 1 ) ),
+				{
+					theme: themeId,
+					changeset_uuid: api.settings.changeset.uuid
+				}
+			) );
+
+			overlay = $( '.wp-full-overlay' );
+			overlay.addClass( 'customize-loading' );
+
+			onceProcessingComplete = function() {
+				var request;
+				if ( api.state( 'processing' ).get() > 0 ) {
+					return;
+				}
+
+				api.state( 'processing' ).unbind( onceProcessingComplete );
+
+				request = api.requestChangesetUpdate();
+				request.done( function() {
+					$( window ).off( 'beforeunload.customize-confirm' );
+					window.location.href = urlParser.href;
+				} );
+				request.fail( function() {
+					overlay.removeClass( 'customize-loading' );
+				} );
+			};
+
+			if ( 0 === api.state( 'processing' ).get() ) {
+				onceProcessingComplete();
+			} else {
+				api.state( 'processing' ).bind( onceProcessingComplete );
+			}
+
+			return deferred.promise();
+		},
+
 		/**
 		 * Render & show the theme details for a given theme model.
 		 *
@@ -1223,7 +1447,7 @@
 		 * @param {Object}   theme
 		 */
 		showDetails: function ( theme, callback ) {
-			var section = this;
+			var section = this, link;
 			callback = callback || function(){};
 			section.currentTheme = theme.id;
 			section.overlay.html( section.template( theme ) )
@@ -1232,6 +1456,22 @@
 			$( 'body' ).addClass( 'modal-open' );
 			section.containFocus( section.overlay );
 			section.updateLimits();
+
+			link = section.overlay.find( '.inactive-theme > a' );
+
+			link.on( 'click', function( event ) {
+				event.preventDefault();
+
+				// Short-circuit if request is currently being made.
+				if ( link.hasClass( 'disabled' ) ) {
+					return;
+				}
+				link.addClass( 'disabled' );
+
+				section.loadThemePreview( theme.id ).fail( function() {
+					link.removeClass( 'disabled' );
+				} );
+			} );
 			callback();
 		},
 
@@ -2227,7 +2467,7 @@
 			wp.ajax.post( 'custom-background-add', {
 				nonce: _wpCustomizeBackground.nonces.add,
 				wp_customize: 'on',
-				theme: api.settings.theme.stylesheet,
+				customize_theme: api.settings.theme.stylesheet,
 				attachment_id: this.params.attachment.id
 			} );
 		}
@@ -2592,7 +2832,7 @@
 
 			// Ensure custom-header-crop Ajax requests bootstrap the Customizer to activate the previewed theme.
 			wp.media.controller.Cropper.prototype.defaults.doCropArgs.wp_customize = 'on';
-			wp.media.controller.Cropper.prototype.defaults.doCropArgs.theme = api.settings.theme.stylesheet;
+			wp.media.controller.Cropper.prototype.defaults.doCropArgs.customize_theme = api.settings.theme.stylesheet;
 		},
 
 		/**
@@ -2883,11 +3123,7 @@
 					return;
 				}
 
-				var previewUrl = $( this ).data( 'previewUrl' );
-
-				$( '.wp-full-overlay' ).addClass( 'customize-loading' );
-
-				window.parent.location = previewUrl;
+				api.section( control.section() ).loadThemePreview( control.params.theme.id );
 			});
 
 			control.container.on( 'click keydown', '.theme-actions .theme-details', function( event ) {
@@ -2948,13 +3184,12 @@
 	 * @mixes wp.customize.Events
 	 */
 	api.PreviewFrame = api.Messenger.extend({
-		sensitivity: 2000,
+		sensitivity: null, // Will get set to api.settings.timeouts.previewFrameSensitivity.
 
 		/**
 		 * Initialize the PreviewFrame.
 		 *
 		 * @param {object} params.container
-		 * @param {object} params.signature
 		 * @param {object} params.previewUrl
 		 * @param {object} params.query
 		 * @param {object} options
@@ -2969,7 +3204,6 @@
 			deferred.promise( this );
 
 			this.container = params.container;
-			this.signature = params.signature;
 
 			$.extend( params, { channel: api.PreviewFrame.uuid() });
 
@@ -2989,143 +3223,118 @@
 		 *                          the request.
 		 */
 		run: function( deferred ) {
-			var self   = this,
+			var previewFrame = this,
 				loaded = false,
-				ready  = false;
+				ready = false,
+				readyData = null,
+				hasPendingChangesetUpdate = '{}' !== previewFrame.query.customized,
+				urlParser,
+				params,
+				form;
 
-			if ( this._ready ) {
-				this.unbind( 'ready', this._ready );
+			if ( previewFrame._ready ) {
+				previewFrame.unbind( 'ready', previewFrame._ready );
 			}
 
-			this._ready = function() {
+			previewFrame._ready = function( data ) {
 				ready = true;
-
-				if ( loaded ) {
-					deferred.resolveWith( self );
-				}
-			};
-
-			this.bind( 'ready', this._ready );
-
-			this.bind( 'ready', function ( data ) {
-
-				this.container.addClass( 'iframe-ready' );
-
+				readyData = data;
+				previewFrame.container.addClass( 'iframe-ready' );
 				if ( ! data ) {
 					return;
 				}
 
-				/*
-				 * Walk over all panels, sections, and controls and set their
-				 * respective active states to true if the preview explicitly
-				 * indicates as such.
-				 */
-				var constructs = {
-					panel: data.activePanels,
-					section: data.activeSections,
-					control: data.activeControls
-				};
-				_( constructs ).each( function ( activeConstructs, type ) {
-					api[ type ].each( function ( construct, id ) {
-						var isDynamicallyCreated = _.isUndefined( api.settings[ type + 's' ][ id ] );
+				if ( loaded ) {
+					deferred.resolveWith( previewFrame, [ data ] );
+				}
+			};
 
-						/*
-						 * If the construct was created statically in PHP (not dynamically in JS)
-						 * then consider a missing (undefined) value in the activeConstructs to
-						 * mean it should be deactivated (since it is gone). But if it is
-						 * dynamically created then only toggle activation if the value is defined,
-						 * as this means that the construct was also then correspondingly
-						 * created statically in PHP and the active callback is available.
-						 * Otherwise, dynamically-created constructs should normally have
-						 * their active states toggled in JS rather than from PHP.
-						 */
-						if ( ! isDynamicallyCreated || ! _.isUndefined( activeConstructs[ id ] ) ) {
-							if ( activeConstructs[ id ] ) {
-								construct.activate();
-							} else {
-								construct.deactivate();
-							}
-						}
-					} );
+			previewFrame.bind( 'ready', previewFrame._ready );
+
+			urlParser = document.createElement( 'a' );
+			urlParser.href = previewFrame.previewUrl();
+
+			params = _.extend(
+				api.utils.parseQueryString( urlParser.search.substr( 1 ) ),
+				{
+					customize_changeset_uuid: previewFrame.query.customize_changeset_uuid,
+					customize_theme: previewFrame.query.customize_theme,
+					customize_messenger_channel: previewFrame.query.customize_messenger_channel
+				}
+			);
+
+			urlParser.search = $.param( params );
+			previewFrame.iframe = $( '<iframe />', {
+				title: api.l10n.previewIframeTitle,
+				name: 'customize-' + previewFrame.channel()
+			} );
+			previewFrame.iframe.attr( 'onmousewheel', '' ); // Workaround for Safari bug. See WP Trac #38149.
+
+			if ( ! hasPendingChangesetUpdate ) {
+				previewFrame.iframe.attr( 'src', urlParser.href );
+			} else {
+				previewFrame.iframe.attr( 'data-src', urlParser.href ); // For debugging purposes.
+			}
+
+			previewFrame.iframe.appendTo( previewFrame.container );
+			previewFrame.targetWindow( previewFrame.iframe[0].contentWindow );
+
+			/*
+			 * Submit customized data in POST request to preview frame window since
+			 * there are setting value changes not yet written to changeset.
+			 */
+			if ( hasPendingChangesetUpdate ) {
+				form = $( '<form>', {
+					action: urlParser.href,
+					target: previewFrame.iframe.attr( 'name' ),
+					method: 'post',
+					hidden: 'hidden'
 				} );
+				form.append( $( '<input>', {
+					type: 'hidden',
+					name: '_method',
+					value: 'GET'
+				} ) );
+				_.each( previewFrame.query, function( value, key ) {
+					form.append( $( '<input>', {
+						type: 'hidden',
+						name: key,
+						value: value
+					} ) );
+				} );
+				previewFrame.container.append( form );
+				form.submit();
+				form.remove(); // No need to keep the form around after submitted.
+			}
 
-				if ( data.settingValidities ) {
-					api._handleSettingValidities( {
-						settingValidities: data.settingValidities,
-						focusInvalidControl: false
-					} );
-				}
-			} );
-
-			this.request = $.ajax( this.previewUrl(), {
-				type: 'POST',
-				data: this.query,
-				xhrFields: {
-					withCredentials: true
-				}
-			} );
-
-			this.request.fail( function() {
-				deferred.rejectWith( self, [ 'request failure' ] );
-			});
-
-			this.request.done( function( response ) {
-				var location = self.request.getResponseHeader('Location'),
-					signature = self.signature,
-					index;
-
-				// Check if the location response header differs from the current URL.
-				// If so, the request was redirected; try loading the requested page.
-				if ( location && location !== self.previewUrl() ) {
-					deferred.rejectWith( self, [ 'redirect', location ] );
-					return;
-				}
+			previewFrame.bind( 'iframe-loading-error', function( error ) {
+				previewFrame.iframe.remove();
 
 				// Check if the user is not logged in.
-				if ( '0' === response ) {
-					self.login( deferred );
+				if ( 0 === error ) {
+					previewFrame.login( deferred );
 					return;
 				}
 
 				// Check for cheaters.
-				if ( '-1' === response ) {
-					deferred.rejectWith( self, [ 'cheatin' ] );
+				if ( -1 === error ) {
+					deferred.rejectWith( previewFrame, [ 'cheatin' ] );
 					return;
 				}
 
-				// Check for a signature in the request.
-				index = response.lastIndexOf( signature );
-				if ( -1 === index || index < response.lastIndexOf('</html>') ) {
-					deferred.rejectWith( self, [ 'unsigned' ] );
-					return;
+				deferred.rejectWith( previewFrame, [ 'request failure' ] );
+			} );
+
+			previewFrame.iframe.one( 'load', function() {
+				loaded = true;
+
+				if ( ready ) {
+					deferred.resolveWith( previewFrame, [ readyData ] );
+				} else {
+					setTimeout( function() {
+						deferred.rejectWith( previewFrame, [ 'ready timeout' ] );
+					}, previewFrame.sensitivity );
 				}
-
-				// Strip the signature from the request.
-				response = response.slice( 0, index ) + response.slice( index + signature.length );
-
-				// Create the iframe and inject the html content.
-				self.iframe = $( '<iframe />', { 'title': api.l10n.previewIframeTitle } ).appendTo( self.container );
-				self.iframe.attr( 'onmousewheel', '' ); // Workaround for Safari bug. See WP Trac #38149.
-
-				// Bind load event after the iframe has been added to the page;
-				// otherwise it will fire when injected into the DOM.
-				self.iframe.one( 'load', function() {
-					loaded = true;
-
-					if ( ready ) {
-						deferred.resolveWith( self );
-					} else {
-						setTimeout( function() {
-							deferred.rejectWith( self, [ 'ready timeout' ] );
-						}, self.sensitivity );
-					}
-				});
-
-				self.targetWindow( self.iframe[0].contentWindow );
-
-				self.targetWindow().document.open();
-				self.targetWindow().document.write( response );
-				self.targetWindow().document.close();
 			});
 		},
 
@@ -3164,26 +3373,29 @@
 
 		destroy: function() {
 			api.Messenger.prototype.destroy.call( this );
-			this.request.abort();
 
-			if ( this.iframe )
+			if ( this.iframe ) {
 				this.iframe.remove();
+			}
 
-			delete this.request;
 			delete this.iframe;
 			delete this.targetWindow;
 		}
 	});
 
 	(function(){
-		var uuid = 0;
+		var id = 0;
 		/**
-		 * Create a universally unique identifier.
+		 * Return an incremented ID for a preview messenger channel.
 		 *
-		 * @return {int}
+		 * This function is named "uuid" for historical reasons, but it is a
+		 * misnomer as it is not an actual UUID, and it is not universally unique.
+		 * This is not to be confused with `api.settings.changeset.uuid`.
+		 *
+		 * @return {string}
 		 */
 		api.PreviewFrame.uuid = function() {
-			return 'preview-' + uuid++;
+			return 'preview-' + String( id++ );
 		};
 	}());
 
@@ -3209,7 +3421,7 @@
 	 * @mixes wp.customize.Events
 	 */
 	api.Previewer = api.Messenger.extend({
-		refreshBuffer: 250,
+		refreshBuffer: null, // Will get set to api.settings.timeouts.windowRefresh.
 
 		/**
 		 * @param {array}  params.allowedUrls
@@ -3217,64 +3429,50 @@
 		 *                                    frame to be placed.
 		 * @param {string} params.form
 		 * @param {string} params.previewUrl  The URL to preview.
-		 * @param {string} params.signature
 		 * @param {object} options
 		 */
 		initialize: function( params, options ) {
-			var self = this,
-				rscheme = /^https?/;
+			var previewer = this,
+				urlParser = document.createElement( 'a' );
 
-			$.extend( this, options || {} );
-			this.deferred = {
+			$.extend( previewer, options || {} );
+			previewer.deferred = {
 				active: $.Deferred()
 			};
 
-			/*
-			 * Wrap this.refresh to prevent it from hammering the servers:
-			 *
-			 * If refresh is called once and no other refresh requests are
-			 * loading, trigger the request immediately.
-			 *
-			 * If refresh is called while another refresh request is loading,
-			 * debounce the refresh requests:
-			 * 1. Stop the loading request (as it is instantly outdated).
-			 * 2. Trigger the new request once refresh hasn't been called for
-			 *    self.refreshBuffer milliseconds.
-			 */
-			this.refresh = (function( self ) {
-				var refresh  = self.refresh,
-					callback = function() {
-						timeout = null;
-						refresh.call( self );
-					},
-					timeout;
-
-				return function() {
-					if ( typeof timeout !== 'number' ) {
-						if ( self.loading ) {
-							self.abort();
+			// Debounce to prevent hammering server and then wait for any pending update requests.
+			previewer.refresh = _.debounce(
+				( function( originalRefresh ) {
+					return function() {
+						var isProcessingComplete, refreshOnceProcessingComplete;
+						isProcessingComplete = function() {
+							return 0 === api.state( 'processing' ).get();
+						};
+						if ( isProcessingComplete() ) {
+							originalRefresh.call( previewer );
 						} else {
-							return callback();
+							refreshOnceProcessingComplete = function() {
+								if ( isProcessingComplete() ) {
+									originalRefresh.call( previewer );
+									api.state( 'processing' ).unbind( refreshOnceProcessingComplete );
+								}
+							};
+							api.state( 'processing' ).bind( refreshOnceProcessingComplete );
 						}
-					}
+					};
+				}( previewer.refresh ) ),
+				previewer.refreshBuffer
+			);
 
-					clearTimeout( timeout );
-					timeout = setTimeout( callback, self.refreshBuffer );
-				};
-			})( this );
-
-			this.container   = api.ensure( params.container );
-			this.allowedUrls = params.allowedUrls;
-			this.signature   = params.signature;
+			previewer.container   = api.ensure( params.container );
+			previewer.allowedUrls = params.allowedUrls;
 
 			params.url = window.location.href;
 
-			api.Messenger.prototype.initialize.call( this, params );
+			api.Messenger.prototype.initialize.call( previewer, params );
 
-			this.add( 'scheme', this.origin() ).link( this.origin ).setter( function( to ) {
-				var match = to.match( rscheme );
-				return match ? match[0] : '';
-			});
+			urlParser.href = previewer.origin();
+			previewer.add( 'scheme', urlParser.protocol.replace( /:$/, '' ) );
 
 			// Limit the URL to internal, front-end links.
 			//
@@ -3284,8 +3482,8 @@
 			// are on different domains to avoid the case where the front end doesn't have
 			// ssl certs.
 
-			this.add( 'previewUrl', params.previewUrl ).setter( function( to ) {
-				var result, urlParser;
+			previewer.add( 'previewUrl', params.previewUrl ).setter( function( to ) {
+				var result, urlParser, newPreviewUrl, schemeMatchingPreviewUrl, queryParams;
 				urlParser = document.createElement( 'a' );
 				urlParser.href = to;
 
@@ -3294,10 +3492,27 @@
 					return null;
 				}
 
+				// Remove state query params.
+				if ( urlParser.search.length > 1 ) {
+					queryParams = api.utils.parseQueryString( urlParser.search.substr( 1 ) );
+					delete queryParams.customize_changeset_uuid;
+					delete queryParams.customize_theme;
+					delete queryParams.customize_messenger_channel;
+					if ( _.isEmpty( queryParams ) ) {
+						urlParser.search = '';
+					} else {
+						urlParser.search = $.param( queryParams );
+					}
+				}
+
+				newPreviewUrl = urlParser.href;
+				urlParser.protocol = previewer.scheme.get() + ':';
+				schemeMatchingPreviewUrl = urlParser.href;
+
 				// Attempt to match the URL to the control frame's scheme
 				// and check if it's allowed. If not, try the original URL.
-				$.each([ to.replace( rscheme, self.scheme() ), to ], function( i, url ) {
-					$.each( self.allowedUrls, function( i, allowed ) {
+				$.each( [ schemeMatchingPreviewUrl, newPreviewUrl ], function( i, url ) {
+					$.each( previewer.allowedUrls, function( i, allowed ) {
 						var path;
 
 						allowed = allowed.replace( /\/+$/, '' );
@@ -3308,31 +3523,172 @@
 							return false;
 						}
 					});
-					if ( result )
+					if ( result ) {
 						return false;
+					}
 				});
 
 				// If we found a matching result, return it. If not, bail.
 				return result ? result : null;
 			});
 
-			// Refresh the preview when the URL is changed (but not yet).
-			this.previewUrl.bind( this.refresh );
+			previewer.bind( 'ready', previewer.ready );
 
-			this.scroll = 0;
-			this.bind( 'scroll', function( distance ) {
-				this.scroll = distance;
+			// Start listening for keep-alive messages when iframe first loads.
+			previewer.deferred.active.done( _.bind( previewer.keepPreviewAlive, previewer ) );
+
+			previewer.bind( 'synced', function() {
+				previewer.send( 'active' );
+			} );
+
+			// Refresh the preview when the URL is changed (but not yet).
+			previewer.previewUrl.bind( previewer.refresh );
+
+			previewer.scroll = 0;
+			previewer.bind( 'scroll', function( distance ) {
+				previewer.scroll = distance;
 			});
 
-			// Update the URL when the iframe sends a URL message.
-			this.bind( 'url', this.previewUrl );
+			// Update the URL when the iframe sends a URL message, resetting scroll position. If URL is unchanged, then refresh.
+			previewer.bind( 'url', function( url ) {
+				var onUrlChange, urlChanged = false;
+				previewer.scroll = 0;
+				onUrlChange = function() {
+					urlChanged = true;
+				};
+				previewer.previewUrl.bind( onUrlChange );
+				previewer.previewUrl.set( url );
+				previewer.previewUrl.unbind( onUrlChange );
+				if ( ! urlChanged ) {
+					previewer.refresh();
+				}
+			} );
 
 			// Update the document title when the preview changes.
-			this.bind( 'documentTitle', function ( title ) {
+			previewer.bind( 'documentTitle', function ( title ) {
 				api.setDocumentTitle( title );
 			} );
 		},
 
+		/**
+		 * Handle the preview receiving the ready message.
+		 *
+		 * @since 4.7.0
+		 *
+		 * @param {object} data - Data from preview.
+		 * @param {string} data.currentUrl - Current URL.
+		 * @param {object} data.activePanels - Active panels.
+		 * @param {object} data.activeSections Active sections.
+		 * @param {object} data.activeControls Active controls.
+		 * @returns {void}
+		 */
+		ready: function( data ) {
+			var previewer = this, synced = {}, constructs;
+
+			synced.settings = api.get();
+			if ( 'resolved' !== previewer.deferred.active.state() || previewer.loading ) {
+				synced.scroll = previewer.scroll;
+			}
+			previewer.send( 'sync', synced );
+
+			// Set the previewUrl without causing the url to set the iframe.
+			if ( data.currentUrl ) {
+				previewer.previewUrl.unbind( previewer.refresh );
+				previewer.previewUrl.set( data.currentUrl );
+				previewer.previewUrl.bind( previewer.refresh );
+			}
+
+			/*
+			 * Walk over all panels, sections, and controls and set their
+			 * respective active states to true if the preview explicitly
+			 * indicates as such.
+			 */
+			constructs = {
+				panel: data.activePanels,
+				section: data.activeSections,
+				control: data.activeControls
+			};
+			_( constructs ).each( function ( activeConstructs, type ) {
+				api[ type ].each( function ( construct, id ) {
+					var isDynamicallyCreated = _.isUndefined( api.settings[ type + 's' ][ id ] );
+
+					/*
+					 * If the construct was created statically in PHP (not dynamically in JS)
+					 * then consider a missing (undefined) value in the activeConstructs to
+					 * mean it should be deactivated (since it is gone). But if it is
+					 * dynamically created then only toggle activation if the value is defined,
+					 * as this means that the construct was also then correspondingly
+					 * created statically in PHP and the active callback is available.
+					 * Otherwise, dynamically-created constructs should normally have
+					 * their active states toggled in JS rather than from PHP.
+					 */
+					if ( ! isDynamicallyCreated || ! _.isUndefined( activeConstructs[ id ] ) ) {
+						if ( activeConstructs[ id ] ) {
+							construct.activate();
+						} else {
+							construct.deactivate();
+						}
+					}
+				} );
+			} );
+
+			if ( data.settingValidities ) {
+				api._handleSettingValidities( {
+					settingValidities: data.settingValidities,
+					focusInvalidControl: false
+				} );
+			}
+		},
+
+		/**
+		 * Keep the preview alive by listening for ready and keep-alive messages.
+		 *
+		 * If a message is not received in the allotted time then the iframe will be set back to the last known valid URL.
+		 *
+		 * @since 4.7.0
+		 *
+		 * @returns {void}
+		 */
+		keepPreviewAlive: function keepPreviewAlive() {
+			var previewer = this, keepAliveTick, timeoutId, handleMissingKeepAlive, scheduleKeepAliveCheck;
+
+			/**
+			 * Schedule a preview keep-alive check.
+			 *
+			 * Note that if a page load takes longer than keepAliveCheck milliseconds,
+			 * the keep-alive messages will still be getting sent from the previous
+			 * URL.
+			 */
+			scheduleKeepAliveCheck = function() {
+				timeoutId = setTimeout( handleMissingKeepAlive, api.settings.timeouts.keepAliveCheck );
+			};
+
+			/**
+			 * Set the previewerAlive state to true when receiving a message from the preview.
+			 */
+			keepAliveTick = function() {
+				api.state( 'previewerAlive' ).set( true );
+				clearTimeout( timeoutId );
+				scheduleKeepAliveCheck();
+			};
+
+			/**
+			 * Set the previewerAlive state to false if keepAliveCheck milliseconds have transpired without a message.
+			 *
+			 * This is most likely to happen in the case of a connectivity error, or if the theme causes the browser
+			 * to navigate to a non-allowed URL. Setting this state to false will force settings with a postMessage
+			 * transport to use refresh instead, causing the preview frame also to be replaced with the current
+			 * allowed preview URL.
+			 */
+			handleMissingKeepAlive = function() {
+				api.state( 'previewerAlive' ).set( false );
+			};
+			scheduleKeepAliveCheck();
+
+			previewer.bind( 'ready', keepAliveTick );
+			previewer.bind( 'keep-alive', keepAliveTick );
+		},
+
 		/**
 		 * Query string data sent with each preview request.
 		 *
@@ -3348,62 +3704,59 @@
 		},
 
 		/**
-		 * Refresh the preview.
+		 * Refresh the preview seamlessly.
 		 */
 		refresh: function() {
-			var self = this;
+			var previewer = this;
 
 			// Display loading indicator
-			this.send( 'loading-initiated' );
+			previewer.send( 'loading-initiated' );
 
-			this.abort();
+			previewer.abort();
 
-			this.loading = new api.PreviewFrame({
-				url:        this.url(),
-				previewUrl: this.previewUrl(),
-				query:      this.query() || {},
-				container:  this.container,
-				signature:  this.signature
+			previewer.loading = new api.PreviewFrame({
+				url:        previewer.url(),
+				previewUrl: previewer.previewUrl(),
+				query:      previewer.query( { excludeCustomizedSaved: true } ) || {},
+				container:  previewer.container
 			});
 
-			this.loading.done( function() {
-				// 'this' is the loading frame
-				this.bind( 'synced', function() {
-					if ( self.preview )
-						self.preview.destroy();
-					self.preview = this;
-					delete self.loading;
+			previewer.loading.done( function( readyData ) {
+				var loadingFrame = this, previousPreview, onceSynced;
 
-					self.targetWindow( this.targetWindow() );
-					self.channel( this.channel() );
+				previousPreview = previewer.preview;
+				previewer.preview = loadingFrame;
+				previewer.targetWindow( loadingFrame.targetWindow() );
+				previewer.channel( loadingFrame.channel() );
 
-					self.deferred.active.resolve();
-					self.send( 'active' );
-				});
+				onceSynced = function() {
+					loadingFrame.unbind( 'synced', onceSynced );
+					if ( previousPreview ) {
+						previousPreview.destroy();
+					}
+					previewer.deferred.active.resolve();
+					delete previewer.loading;
+				};
+				loadingFrame.bind( 'synced', onceSynced );
 
-				this.send( 'sync', {
-					scroll:   self.scroll,
-					settings: api.get()
-				});
+				// This event will be received directly by the previewer in normal navigation; this is only needed for seamless refresh.
+				previewer.trigger( 'ready', readyData );
 			});
 
-			this.loading.fail( function( reason, location ) {
-				self.send( 'loading-failed' );
-				if ( 'redirect' === reason && location ) {
-					self.previewUrl( location );
-				}
+			previewer.loading.fail( function( reason ) {
+				previewer.send( 'loading-failed' );
 
 				if ( 'logged out' === reason ) {
-					if ( self.preview ) {
-						self.preview.destroy();
-						delete self.preview;
+					if ( previewer.preview ) {
+						previewer.preview.destroy();
+						delete previewer.preview;
 					}
 
-					self.login().done( self.refresh );
+					previewer.login().done( previewer.refresh );
 				}
 
 				if ( 'cheatin' === reason ) {
-					self.cheatin();
+					previewer.cheatin();
 				}
 			});
 		},
@@ -3463,7 +3816,7 @@
 
 			request = wp.ajax.post( 'customize_refresh_nonces', {
 				wp_customize: 'on',
-				theme: api.settings.theme.stylesheet
+				customize_theme: api.settings.theme.stylesheet
 			});
 
 			request.done( function( response ) {
@@ -3679,6 +4032,13 @@
 			return;
 		}
 
+		if ( null === api.PreviewFrame.prototype.sensitivity ) {
+			api.PreviewFrame.prototype.sensitivity = api.settings.timeouts.previewFrameSensitivity;
+		}
+		if ( null === api.Previewer.prototype.refreshBuffer ) {
+			api.Previewer.prototype.refreshBuffer = api.settings.timeouts.windowRefresh;
+		}
+
 		var parent,
 			body = $( document.body ),
 			overlay = body.children( '.wp-full-overlay' ),
@@ -3722,8 +4082,7 @@
 			container:   '#customize-preview',
 			form:        '#customize-controls',
 			previewUrl:  api.settings.url.preview,
-			allowedUrls: api.settings.url.allowed,
-			signature:   'WP_CUSTOMIZER_SIGNATURE'
+			allowedUrls: api.settings.url.allowed
 		}, {
 
 			nonce: api.settings.nonce,
@@ -3731,26 +4090,51 @@
 			/**
 			 * Build the query to send along with the Preview request.
 			 *
-			 * @return {object}
+			 * @since 4.7.0 Added options param.
+			 *
+			 * @param {object}  [options] Options.
+			 * @param {boolean} [options.excludeCustomizedSaved=false] Exclude saved settings in customized response (values pending writing to changeset).
+			 * @return {object} Query vars.
 			 */
-			query: function() {
-				var dirtyCustomized = {};
-				api.each( function ( value, key ) {
-					if ( value._dirty ) {
-						dirtyCustomized[ key ] = value();
-					}
-				} );
-
-				return {
+			query: function( options ) {
+				var queryVars = {
 					wp_customize: 'on',
-					theme:      api.settings.theme.stylesheet,
-					customized: JSON.stringify( dirtyCustomized ),
-					nonce:      this.nonce.preview
+					customize_theme: api.settings.theme.stylesheet,
+					nonce: this.nonce.preview,
+					customize_changeset_uuid: api.settings.changeset.uuid
 				};
+
+				/*
+				 * Exclude customized data if requested especially for calls to requestChangesetUpdate.
+				 * Changeset updates are differential and so it is a performance waste to send all of
+				 * the dirty settings with each update.
+				 */
+				queryVars.customized = JSON.stringify( api.dirtyValues( {
+					unsaved: options && options.excludeCustomizedSaved
+				} ) );
+
+				return queryVars;
 			},
 
-			save: function() {
-				var self = this,
+			/**
+			 * Save (and publish) the customizer changeset.
+			 *
+			 * Updates to the changeset are transactional. If any of the settings
+			 * are invalid then none of them will be written into the changeset.
+			 * A revision will be made for the changeset post if revisions support
+			 * has been added to the post type.
+			 *
+			 * @param {object} [args] Args.
+			 * @param {string} [args.status=publish] Status.
+			 * @param {string} [args.date] Date, in local time in MySQL format.
+			 * @param {string} [args.title] Title
+			 *
+			 * @returns {jQuery.promise}
+			 */
+			save: function( args ) {
+				var previewer = this,
+					deferred = $.Deferred(),
+					changesetStatus = 'publish',
 					processing = api.state( 'processing' ),
 					submitWhenDoneProcessing,
 					submit,
@@ -3758,7 +4142,16 @@
 					invalidSettings = [],
 					invalidControls;
 
-				body.addClass( 'saving' );
+				if ( args && args.status ) {
+					changesetStatus = args.status;
+				}
+
+				if ( api.state( 'saving' ).get() ) {
+					deferred.reject( 'already_saving' );
+					deferred.promise();
+				}
+
+				api.state( 'saving' ).set( true );
 
 				function captureSettingModifiedDuringSave( setting ) {
 					modifiedWhileSaving[ setting.id ] = true;
@@ -3766,7 +4159,7 @@
 				api.bind( 'change', captureSettingModifiedDuringSave );
 
 				submit = function () {
-					var request, query;
+					var request, query, settingInvalidities = {};
 
 					/*
 					 * Block saving if there are any settings that are marked as
@@ -3777,20 +4170,50 @@
 						setting.notifications.each( function( notification ) {
 							if ( 'error' === notification.type && ! notification.fromServer ) {
 								invalidSettings.push( setting.id );
+								if ( ! settingInvalidities[ setting.id ] ) {
+									settingInvalidities[ setting.id ] = {};
+								}
+								settingInvalidities[ setting.id ][ notification.code ] = notification;
 							}
 						} );
 					} );
 					invalidControls = api.findControlsForSettings( invalidSettings );
 					if ( ! _.isEmpty( invalidControls ) ) {
 						_.values( invalidControls )[0][0].focus();
-						body.removeClass( 'saving' );
 						api.unbind( 'change', captureSettingModifiedDuringSave );
-						return;
+						deferred.rejectWith( previewer, [
+							{ setting_invalidities: settingInvalidities }
+						] );
+						api.state( 'saving' ).set( false );
+						return deferred.promise();
 					}
 
-					query = $.extend( self.query(), {
-						nonce:  self.nonce.save
+					/*
+					 * Note that excludeCustomizedSaved is intentionally false so that the entire
+					 * set of customized data will be included if bypassed changeset update.
+					 */
+					query = $.extend( previewer.query( { excludeCustomizedSaved: false } ), {
+						nonce: previewer.nonce.save,
+						customize_changeset_status: changesetStatus
 					} );
+					if ( args && args.date ) {
+						query.customize_changeset_date = args.date;
+					}
+					if ( args && args.title ) {
+						query.customize_changeset_title = args.title;
+					}
+
+					/*
+					 * Note that the dirty customized values will have already been set in the
+					 * changeset and so technically query.customized could be deleted. However,
+					 * it is remaining here to make sure that any settings that got updated
+					 * quietly which may have not triggered an update request will also get
+					 * included in the values that get saved to the changeset. This will ensure
+					 * that values that get injected via the saved event will be included in
+					 * the changeset. This also ensures that setting values that were invalid
+					 * will get re-validated, perhaps in the case of settings that are invalid
+					 * due to dependencies on other settings.
+					 */
 					request = wp.ajax.post( 'customize_save', query );
 
 					// Disable save button during the save request.
@@ -3799,12 +4222,13 @@
 					api.trigger( 'save', request );
 
 					request.always( function () {
-						body.removeClass( 'saving' );
+						api.state( 'saving' ).set( false );
 						saveBtn.prop( 'disabled', false );
 						api.unbind( 'change', captureSettingModifiedDuringSave );
 					} );
 
 					request.fail( function ( response ) {
+
 						if ( '0' === response ) {
 							response = 'not_logged_in';
 						} else if ( '-1' === response ) {
@@ -3813,12 +4237,12 @@
 						}
 
 						if ( 'invalid_nonce' === response ) {
-							self.cheatin();
+							previewer.cheatin();
 						} else if ( 'not_logged_in' === response ) {
-							self.preview.iframe.hide();
-							self.login().done( function() {
-								self.save();
-								self.preview.iframe.show();
+							previewer.preview.iframe.hide();
+							previewer.login().done( function() {
+								previewer.save();
+								previewer.preview.iframe.show();
 							} );
 						}
 
@@ -3829,19 +4253,20 @@
 							} );
 						}
 
+						deferred.rejectWith( previewer, [ response ] );
 						api.trigger( 'error', response );
 					} );
 
 					request.done( function( response ) {
 
-						// Clear setting dirty states, if setting wasn't modified while saving.
-						api.each( function( setting ) {
-							if ( ! modifiedWhileSaving[ setting.id ] ) {
-								setting._dirty = false;
-							}
-						} );
+						previewer.send( 'saved', response );
 
-						api.previewer.send( 'saved', response );
+						api.state( 'changesetStatus' ).set( response.changeset_status );
+						if ( 'publish' === response.changeset_status ) {
+							api.state( 'changesetStatus' ).set( '' );
+							api.settings.changeset.uuid = response.next_changeset_uuid;
+							parent.send( 'changeset-uuid', api.settings.changeset.uuid );
+						}
 
 						if ( response.setting_validities ) {
 							api._handleSettingValidities( {
@@ -3850,6 +4275,7 @@
 							} );
 						}
 
+						deferred.resolveWith( previewer, [ response ] );
 						api.trigger( 'saved', response );
 
 						// Restore the global dirty state if any settings were modified during save.
@@ -3871,6 +4297,7 @@
 					api.state.bind( 'change', submitWhenDoneProcessing );
 				}
 
+				return deferred.promise();
 			}
 		});
 
@@ -3957,55 +4384,71 @@
 
 		api.bind( 'ready', api.reflowPaneContents );
 		$( [ api.panel, api.section, api.control ] ).each( function ( i, values ) {
-			var debouncedReflowPaneContents = _.debounce( api.reflowPaneContents, 100 );
+			var debouncedReflowPaneContents = _.debounce( api.reflowPaneContents, api.settings.timeouts.reflowPaneContents );
 			values.bind( 'add', debouncedReflowPaneContents );
 			values.bind( 'change', debouncedReflowPaneContents );
 			values.bind( 'remove', debouncedReflowPaneContents );
 		} );
 
-		// Check if preview url is valid and load the preview frame.
-		if ( api.previewer.previewUrl() ) {
-			api.previewer.refresh();
-		} else {
-			api.previewer.previewUrl( api.settings.url.home );
-		}
-
 		// Save and activated states
 		(function() {
 			var state = new api.Values(),
 				saved = state.create( 'saved' ),
+				saving = state.create( 'saving' ),
 				activated = state.create( 'activated' ),
 				processing = state.create( 'processing' ),
-				paneVisible = state.create( 'paneVisible' );
+				paneVisible = state.create( 'paneVisible' ),
+				changesetStatus = state.create( 'changesetStatus' ),
+				previewerAlive = state.create( 'previewerAlive' ),
+				populateChangesetUuidParam;
 
 			state.bind( 'change', function() {
+				var canSave;
+
 				if ( ! activated() ) {
-					saveBtn.val( api.l10n.activate ).prop( 'disabled', false );
+					saveBtn.val( api.l10n.activate );
 					closeBtn.find( '.screen-reader-text' ).text( api.l10n.cancel );
 
-				} else if ( saved() ) {
-					saveBtn.val( api.l10n.saved ).prop( 'disabled', true );
+				} else if ( '' === changesetStatus.get() && saved() ) {
+					saveBtn.val( api.l10n.saved );
 					closeBtn.find( '.screen-reader-text' ).text( api.l10n.close );
 
 				} else {
-					saveBtn.val( api.l10n.save ).prop( 'disabled', false );
+					saveBtn.val( api.l10n.save );
 					closeBtn.find( '.screen-reader-text' ).text( api.l10n.cancel );
 				}
+
+				/*
+				 * Save (publish) button should be enabled if saving is not currently happening,
+				 * and if the theme is not active or the changeset exists but is not published.
+				 */
+				canSave = ! saving() && ( ! activated() || ! saved() || ( '' !== changesetStatus() && 'publish' !== changesetStatus() ) );
+
+				saveBtn.prop( 'disabled', ! canSave );
 			});
 
 			// Set default states.
 			saved( true );
+			saving( false );
 			activated( api.settings.theme.active );
 			processing( 0 );
 			paneVisible( true );
+			previewerAlive( true );
+			changesetStatus( api.settings.changeset.status );
 
 			api.bind( 'change', function() {
 				state('saved').set( false );
 			});
 
-			api.bind( 'saved', function() {
+			saving.bind( function( isSaving ) {
+				body.toggleClass( 'saving', isSaving );
+			} );
+
+			api.bind( 'saved', function( response ) {
 				state('saved').set( true );
-				state('activated').set( true );
+				if ( 'publish' === response.changeset_status ) {
+					state( 'activated' ).set( true );
+				}
 			});
 
 			activated.bind( function( to ) {
@@ -4014,10 +4457,48 @@
 				}
 			});
 
+			populateChangesetUuidParam = function( isIncluded ) {
+				var urlParser, queryParams;
+				urlParser = document.createElement( 'a' );
+				urlParser.href = location.href;
+				queryParams = api.utils.parseQueryString( urlParser.search.substr( 1 ) );
+				if ( isIncluded ) {
+					if ( queryParams.changeset_uuid === api.settings.changeset.uuid ) {
+						return;
+					}
+					queryParams.changeset_uuid = api.settings.changeset.uuid;
+				} else {
+					if ( ! queryParams.changeset_uuid ) {
+						return;
+					}
+					delete queryParams.changeset_uuid;
+				}
+				urlParser.search = $.param( queryParams );
+				history.replaceState( {}, document.title, urlParser.href );
+			};
+
+			if ( history.replaceState ) {
+				saved.bind( function( isSaved ) {
+					if ( ! isSaved ) {
+						populateChangesetUuidParam( true );
+					}
+				} );
+				changesetStatus.bind( function( newStatus ) {
+					populateChangesetUuidParam( '' !== newStatus );
+				} );
+			}
+
 			// Expose states to the API.
 			api.state = state;
 		}());
 
+		// Check if preview url is valid and load the preview frame.
+		if ( api.previewer.previewUrl() ) {
+			api.previewer.refresh();
+		} else {
+			api.previewer.previewUrl( api.settings.url.home );
+		}
+
 		// Button bindings.
 		saveBtn.click( function( event ) {
 			api.previewer.save();
@@ -4169,7 +4650,7 @@
 		});
 
 		// Prompt user with AYS dialog if leaving the Customizer with unsaved changes
-		$( window ).on( 'beforeunload', function () {
+		$( window ).on( 'beforeunload.customize-confirm', function () {
 			if ( ! api.state( 'saved' )() ) {
 				setTimeout( function() {
 					overlay.removeClass( 'customize-loading' );
@@ -4190,6 +4671,8 @@
 			parent.send( 'title', newTitle );
 		});
 
+		parent.send( 'changeset-uuid', api.settings.changeset.uuid );
+
 		// Initialize the connection with the parent frame.
 		parent.send( 'ready' );
 
@@ -4292,6 +4775,51 @@
 			api.previewer.refresh();
 		});
 
+		// Autosave changeset.
+		( function() {
+			var timeoutId, updateChangesetWithReschedule, scheduleChangesetUpdate, updatePending = false;
+
+			/**
+			 * Request changeset update and then re-schedule the next changeset update time.
+			 *
+			 * @private
+			 */
+			updateChangesetWithReschedule = function() {
+				if ( ! updatePending ) {
+					updatePending = true;
+					api.requestChangesetUpdate().always( function() {
+						updatePending = false;
+					} );
+				}
+				scheduleChangesetUpdate();
+			};
+
+			/**
+			 * Schedule changeset update.
+			 *
+			 * @private
+			 */
+			scheduleChangesetUpdate = function() {
+				clearTimeout( timeoutId );
+				timeoutId = setTimeout( function() {
+					updateChangesetWithReschedule();
+				}, api.settings.timeouts.changesetAutoSave );
+			};
+
+			// Start auto-save interval for updating changeset.
+			scheduleChangesetUpdate();
+
+			// Save changeset when focus removed from window.
+			$( window ).on( 'blur.wp-customize-changeset-update', function() {
+				updateChangesetWithReschedule();
+			} );
+
+			// Save changeset before unloading window.
+			$( window ).on( 'beforeunload.wp-customize-changeset-update', function() {
+				updateChangesetWithReschedule();
+			} );
+		} ());
+
 		api.trigger( 'ready' );
 	});
 
diff --git a/wp-admin/js/customize-controls.min.js b/wp-admin/js/customize-controls.min.js
index 693df23ac3..cad2f1958b 100644
--- a/wp-admin/js/customize-controls.min.js
+++ b/wp-admin/js/customize-controls.min.js
@@ -1,2 +1,2 @@
-!function(a,b){var c,d,e,f=wp.customize;f.Setting=f.Value.extend({initialize:function(a,b,c){f.Value.prototype.initialize.call(this,b,c),this.id=a,this.transport=this.transport||"refresh",this._dirty=c.dirty||!1,this.notifications=new f.Values({defaultConstructor:f.Notification}),this.bind(this.preview)},preview:function(){switch(this.transport){case"refresh":return this.previewer.refresh();case"postMessage":return this.previewer.send("setting",[this.id,this()])}},findControls:function(){var a=this,b=[];return f.control.each(function(c){_.each(c.settings,function(d){d.id===a.id&&b.push(c)})}),b}}),f.utils={},f.utils.bubbleChildValueChanges=function(a,c){b.each(c,function(b,c){a[c].bind(function(b,c){a.parent&&b!==c&&a.parent.trigger("change",a)})})},d=function(a){var b,c,d,e;b=this,a=a||{},d=function(){var a;a=(b.extended(f.Panel)||b.extended(f.Section))&&b.expanded&&b.expanded()?b.contentContainer:b.container,e=a.find(".control-focus:first"),0===e.length&&(e=a.find("input, select, textarea, button, object, a[href], [tabindex]").filter(":visible").first()),e.focus()},a.completeCallback?(c=a.completeCallback,a.completeCallback=function(){d(),c()}):a.completeCallback=d,f.state("paneVisible").set(!0),b.expand?b.expand(a):a.completeCallback()},f.utils.prioritySort=function(a,b){return a.priority()===b.priority()&&"number"==typeof a.params.instanceNumber&&"number"==typeof b.params.instanceNumber?a.params.instanceNumber-b.params.instanceNumber:a.priority()-b.priority()},f.utils.isKeydownButNotEnterEvent=function(a){return"keydown"===a.type&&13!==a.which},f.utils.areElementListsEqual=function(a,c){var d=a.length===c.length&&-1===_.indexOf(_.map(_.zip(a,c),function(a){return b(a[0]).is(a[1])}),!1);return d},e=function(){var a,b,c;return a=document.createElement("div"),b={transition:"transitionend",OTransition:"oTransitionEnd",MozTransition:"transitionend",WebkitTransition:"webkitTransitionEnd"},c=_.find(_.keys(b),function(b){return!_.isUndefined(a.style[b])}),c?b[c]:null}(),c=f.Class.extend({defaultActiveArguments:{duration:"fast",completeCallback:b.noop},defaultExpandedArguments:{duration:"fast",completeCallback:b.noop},containerType:"container",defaults:{title:"",description:"",priority:100,type:"default",content:null,active:!0,instanceNumber:null},initialize:function(a,c){var d=this;d.id=a,c=c||{},c.params=_.defaults(c.params||{},d.defaults),b.extend(d,c),d.templateSelector="customize-"+d.containerType+"-"+d.params.type,d.container=b(d.params.content),0===d.container.length&&(d.container=b(d.getContainer())),d.headContainer=d.container,d.contentContainer=d.getContent(),d.container=d.container.add(d.contentContainer),d.deferred={embedded:new b.Deferred},d.priority=new f.Value,d.active=new f.Value,d.activeArgumentsQueue=[],d.expanded=new f.Value,d.expandedArgumentsQueue=[],d.active.bind(function(a){var c=d.activeArgumentsQueue.shift();c=b.extend({},d.defaultActiveArguments,c),a=a&&d.isContextuallyActive(),d.onChangeActive(a,c)}),d.expanded.bind(function(a){var c=d.expandedArgumentsQueue.shift();c=b.extend({},d.defaultExpandedArguments,c),d.onChangeExpanded(a,c)}),d.deferred.embedded.done(function(){d.attachEvents()}),f.utils.bubbleChildValueChanges(d,["priority","active"]),d.priority.set(d.params.priority),d.active.set(d.params.active),d.expanded.set(!1)},ready:function(){},_children:function(a,b){var c=this,d=[];return f[b].each(function(b){b[a].get()===c.id&&d.push(b)}),d.sort(f.utils.prioritySort),d},isContextuallyActive:function(){throw new Error("Container.isContextuallyActive() must be overridden in a subclass.")},onChangeActive:function(a,c){var d,e,g=this,h=g.headContainer;return c.unchanged?void(c.completeCallback&&c.completeCallback()):(d="resolved"===f.previewer.deferred.active.state()?c.duration:0,g.extended(f.Panel)&&(f.panel.each(function(a){a!==g&&a.expanded()&&(e=a,d=0)}),a||_.each(g.sections(),function(a){a.collapse({duration:0})})),void(b.contains(document,h)?a?h.stop(!0,!0).slideDown(d,c.completeCallback):g.expanded()?g.collapse({duration:d,completeCallback:function(){h.stop(!0,!0).slideUp(d,c.completeCallback)}}):h.stop(!0,!0).slideUp(d,c.completeCallback):(h.toggle(a),c.completeCallback&&c.completeCallback())))},_toggleActive:function(a,b){var c=this;return b=b||{},a&&this.active.get()||!a&&!this.active.get()?(b.unchanged=!0,c.onChangeActive(c.active.get(),b),!1):(b.unchanged=!1,this.activeArgumentsQueue.push(b),this.active.set(a),!0)},activate:function(a){return this._toggleActive(!0,a)},deactivate:function(a){return this._toggleActive(!1,a)},onChangeExpanded:function(){throw new Error("Must override with subclass.")},_toggleExpanded:function(a,b){var c,d=this;return b=b||{},c=b.completeCallback,a&&!d.active()?!1:(f.state("paneVisible").set(!0),b.completeCallback=function(){c&&c.apply(d,arguments),a?d.container.trigger("expanded"):d.container.trigger("collapsed")},a&&d.expanded.get()||!a&&!d.expanded.get()?(b.unchanged=!0,d.onChangeExpanded(d.expanded.get(),b),!1):(b.unchanged=!1,d.expandedArgumentsQueue.push(b),d.expanded.set(a),!0))},expand:function(a){return this._toggleExpanded(!0,a)},collapse:function(a){return this._toggleExpanded(!1,a)},_animateChangeExpanded:function(a){if(!e)return void(a&&a());var c,d,f=this,g=f.contentContainer,h=g.closest(".wp-full-overlay");c=h.add(g),(_.isUndefined(f.panel)||""===f.panel())&&(c=c.add("#customize-info, .customize-pane-parent")),d=function(f){2===f.eventPhase&&b(f.target).is(g)&&(g.off(e,d),c.removeClass("busy"),a&&a())},g.on(e,d),c.addClass("busy"),_.defer(function(){var a=g.closest(".wp-full-overlay-sidebar-content"),b=a.scrollTop(),c=g.data("previous-scrollTop")||0,d=f.expanded();d&&b>0?(g.css("top",b+"px"),g.data("previous-scrollTop",b)):!d&&b+c>0&&(g.css("top",c-b+"px"),a.scrollTop(c))})},focus:d,getContainer:function(){var a,c=this;return a=0!==b("#tmpl-"+c.templateSelector).length?wp.template(c.templateSelector):wp.template("customize-"+c.containerType+"-default"),a&&c.container?b.trim(a(c.params)):"<li></li>"},getContent:function(){var a=this,b=a.container,c=b.find(".accordion-section-content, .control-panel-content").first(),d="sub-"+b.attr("id"),e=d,f=b.attr("aria-owns");return f&&(e=e+" "+f),b.attr("aria-owns",e),c.detach().attr({id:d,"class":"customize-pane-child "+c.attr("class")+" "+b.attr("class")})}}),f.Section=c.extend({containerType:"section",defaults:{title:"",description:"",priority:100,type:"default",content:null,active:!0,instanceNumber:null,panel:null,customizeAction:""},initialize:function(a,d){var e=this;c.prototype.initialize.call(e,a,d),e.id=a,e.panel=new f.Value,e.panel.bind(function(a){b(e.headContainer).toggleClass("control-subsection",!!a)}),e.panel.set(e.params.panel||""),f.utils.bubbleChildValueChanges(e,["panel"]),e.embed(),e.deferred.embedded.done(function(){e.ready()})},embed:function(){var a,c=this,d=b("#customize-theme-controls");a=function(a){var e;a?f.panel(a,function(a){a.deferred.embedded.done(function(){e=a.contentContainer,c.headContainer.parent().is(e)||e.append(c.headContainer),c.contentContainer.parent().is(c.headContainer)||d.append(c.contentContainer),c.deferred.embedded.resolve()})}):(e=b(".customize-pane-parent"),c.headContainer.parent().is(e)||e.append(c.headContainer),c.contentContainer.parent().is(c.headContainer)||d.append(c.contentContainer),c.deferred.embedded.resolve())},c.panel.bind(a),a(c.panel.get())},attachEvents:function(){var a=this;a.container.find(".accordion-section-title, .customize-section-back").on("click keydown",function(b){f.utils.isKeydownButNotEnterEvent(b)||(b.preventDefault(),a.expanded()?a.collapse():a.expand())})},isContextuallyActive:function(){var a=this,b=a.controls(),c=0;return _(b).each(function(a){a.active()&&(c+=1)}),0!==c},controls:function(){return this._children("section","control")},onChangeExpanded:function(a,c){var d,e=this,g=e.headContainer.closest(".wp-full-overlay-sidebar-content"),h=e.contentContainer,i=e.headContainer.closest(".wp-full-overlay"),j=h.find(".customize-section-back"),k=e.headContainer.find(".accordion-section-title").first();a&&!h.hasClass("open")?(d=c.unchanged?c.completeCallback:b.proxy(function(){e._animateChangeExpanded(function(){k.attr("tabindex","-1"),j.attr("tabindex","0"),j.focus(),h.css("top",""),g.scrollTop(0),c.completeCallback&&c.completeCallback()}),h.addClass("open"),i.addClass("section-open")},this),c.allowMultiple||f.section.each(function(a){a!==e&&a.collapse({duration:c.duration})}),e.panel()?f.panel(e.panel()).expand({duration:c.duration,completeCallback:d}):(f.panel.each(function(a){a.collapse()}),d())):!a&&h.hasClass("open")?(e._animateChangeExpanded(function(){j.attr("tabindex","-1"),k.attr("tabindex","0"),k.focus(),h.css("top",""),c.completeCallback&&c.completeCallback()}),h.removeClass("open"),i.removeClass("section-open")):c.completeCallback&&c.completeCallback()}}),f.ThemesSection=f.Section.extend({currentTheme:"",overlay:"",template:"",screenshotQueue:null,$window:b(window),initialize:function(){return this.$customizeSidebar=b(".wp-full-overlay-sidebar-content:first"),f.Section.prototype.initialize.apply(this,arguments)},ready:function(){var a=this;a.overlay=a.container.find(".theme-overlay"),a.template=wp.template("customize-themes-details-view"),b("body").on("keyup",function(b){a.overlay.find(".theme-wrap").is(":visible")&&(39===b.keyCode&&a.nextTheme(),37===b.keyCode&&a.previousTheme(),27===b.keyCode&&a.closeDetails())}),_.bindAll(this,"renderScreenshots")},isContextuallyActive:function(){return this.active()},attachEvents:function(){var a=this;a.container.find(".change-theme, .customize-theme").on("click keydown",function(b){f.utils.isKeydownButNotEnterEvent(b)||(b.preventDefault(),a.expanded()?a.collapse():a.expand())}),a.container.on("click keydown",".left",function(b){f.utils.isKeydownButNotEnterEvent(b)||(b.preventDefault(),a.previousTheme())}),a.container.on("click keydown",".right",function(b){f.utils.isKeydownButNotEnterEvent(b)||(b.preventDefault(),a.nextTheme())}),a.container.on("click keydown",".theme-backdrop, .close",function(b){f.utils.isKeydownButNotEnterEvent(b)||(b.preventDefault(),a.closeDetails())});var b=_.throttle(_.bind(a.renderScreenshots,this),100);a.container.on("input","#themes-filter",function(c){var d,e=c.currentTarget.value.toLowerCase().trim().replace("-"," "),f=a.controls();_.each(f,function(a){a.filter(e)}),b(),d=a.container.find("li.customize-control:visible").length,a.container.find(".theme-count").text(d)}),f.bind("ready",function(){_.each(a.controls().slice(0,3),function(a){var b,c=a.params.theme.screenshot[0];c&&(b=new Image,b.src=c)})})},onChangeExpanded:function(a,b){if(b.unchanged)return void(b.completeCallback&&b.completeCallback());var c=this,d=c.contentContainer,e=d.closest(".wp-full-overlay"),g=d.closest(".wp-full-overlay-sidebar-content"),h=d.find(".customize-theme"),i=c.headContainer.find(".change-theme");a&&!d.hasClass("current-panel")?(f.section.each(function(a){a!==c&&a.collapse({duration:b.duration})}),f.panel.each(function(a){a.collapse({duration:0})}),c._animateChangeExpanded(function(){i.attr("tabindex","-1"),h.attr("tabindex","0"),h.focus(),d.css("top",""),g.scrollTop(0),b.completeCallback&&b.completeCallback()}),e.addClass("in-themes-panel"),d.addClass("current-panel")):!a&&d.hasClass("current-panel")&&(c._animateChangeExpanded(function(){i.attr("tabindex","0"),h.attr("tabindex","-1"),i.focus(),d.css("top",""),b.completeCallback&&b.completeCallback()}),e.removeClass("in-themes-panel"),d.removeClass("current-panel"))},renderScreenshots:function(){var a=this;null===a.screenshotQueue&&(a.screenshotQueue=a.controls()),a.screenshotQueue.length&&(a.screenshotQueue=_.filter(a.screenshotQueue,function(b){var c=b.container.find(".theme-screenshot"),d=c.find("img");if(!d.length)return!1;if(d.is(":hidden"))return!0;var e=a.$window.scrollTop(),f=e+a.$window.height(),g=d.offset().top,h=c.height(),i=g+h,j=3*h,k=i>=e-j&&f+j>=g;return k&&b.container.trigger("render-screenshot"),!k}))},nextTheme:function(){var a=this;a.getNextTheme()&&a.showDetails(a.getNextTheme(),function(){a.overlay.find(".right").focus()})},getNextTheme:function(){var a,b;return a=f.control("theme_"+this.currentTheme),b=a.container.next("li.customize-control-theme"),b.length?(b=b[0].id.replace("customize-control-",""),a=f.control(b),a.params.theme):!1},previousTheme:function(){var a=this;a.getPreviousTheme()&&a.showDetails(a.getPreviousTheme(),function(){a.overlay.find(".left").focus()})},getPreviousTheme:function(){var a,b;return a=f.control("theme_"+this.currentTheme),b=a.container.prev("li.customize-control-theme"),b.length?(b=b[0].id.replace("customize-control-",""),a=f.control(b),a.params.theme):!1},updateLimits:function(){this.getNextTheme()||this.overlay.find(".right").addClass("disabled"),this.getPreviousTheme()||this.overlay.find(".left").addClass("disabled")},showDetails:function(a,c){var d=this;c=c||function(){},d.currentTheme=a.id,d.overlay.html(d.template(a)).fadeIn("fast").focus(),b("body").addClass("modal-open"),d.containFocus(d.overlay),d.updateLimits(),c()},closeDetails:function(){b("body").removeClass("modal-open"),this.overlay.fadeOut("fast"),f.control("theme_"+this.currentTheme).focus()},containFocus:function(a){var c;a.on("keydown",function(d){return 9===d.keyCode?(c=b(":tabbable",a),c.last()[0]!==d.target||d.shiftKey?c.first()[0]===d.target&&d.shiftKey?(c.last().focus(),!1):void 0:(c.first().focus(),!1)):void 0})}}),f.Panel=c.extend({containerType:"panel",initialize:function(a,b){var d=this;c.prototype.initialize.call(d,a,b),d.embed(),d.deferred.embedded.done(function(){d.ready()})},embed:function(){var a=this,c=b("#customize-theme-controls"),d=b(".customize-pane-parent");a.headContainer.parent().is(d)||d.append(a.headContainer),a.contentContainer.parent().is(a.headContainer)||(c.append(a.contentContainer),a.renderContent()),a.deferred.embedded.resolve()},attachEvents:function(){var a,c=this;c.headContainer.find(".accordion-section-title").on("click keydown",function(a){f.utils.isKeydownButNotEnterEvent(a)||(a.preventDefault(),c.expanded()||c.expand())}),c.container.find(".customize-panel-back").on("click keydown",function(a){f.utils.isKeydownButNotEnterEvent(a)||(a.preventDefault(),c.expanded()&&c.collapse())}),a=c.container.find(".panel-meta:first"),a.find("> .accordion-section-title .customize-help-toggle").on("click keydown",function(d){if(!f.utils.isKeydownButNotEnterEvent(d)&&(d.preventDefault(),!a.hasClass("cannot-expand"))){var e=a.find(".customize-panel-description:first");a.hasClass("open")?(a.toggleClass("open"),e.slideUp(c.defaultExpandedArguments.duration),b(this).attr("aria-expanded",!1)):(e.slideDown(c.defaultExpandedArguments.duration),a.toggleClass("open"),b(this).attr("aria-expanded",!0))}})},sections:function(){return this._children("panel","section")},isContextuallyActive:function(){var a=this,b=a.sections(),c=0;return _(b).each(function(a){a.active()&&a.isContextuallyActive()&&(c+=1)}),0!==c},onChangeExpanded:function(a,b){if(b.unchanged)return void(b.completeCallback&&b.completeCallback());var c=this,d=c.contentContainer,e=d.closest(".wp-full-overlay"),g=d.closest(".wp-full-overlay-sidebar-content"),h=c.headContainer.find(".accordion-section-title"),i=d.find(".customize-panel-back");a&&!d.hasClass("current-panel")?(f.section.each(function(a){c.id!==a.panel()&&a.collapse({duration:0})}),f.panel.each(function(a){c!==a&&a.collapse({duration:0})}),c._animateChangeExpanded(function(){h.attr("tabindex","-1"),i.attr("tabindex","0"),i.focus(),d.css("top",""),g.scrollTop(0),b.completeCallback&&b.completeCallback()}),e.addClass("in-sub-panel"),d.addClass("current-panel")):!a&&d.hasClass("current-panel")&&(c._animateChangeExpanded(function(){h.attr("tabindex","0"),i.attr("tabindex","-1"),h.focus(),d.css("top",""),b.completeCallback&&b.completeCallback()}),e.removeClass("in-sub-panel"),d.removeClass("current-panel"))},renderContent:function(){var a,c=this;a=0!==b("#tmpl-"+c.templateSelector+"-content").length?wp.template(c.templateSelector+"-content"):wp.template("customize-panel-default-content"),a&&c.headContainer&&c.contentContainer.html(a(c.params))}}),f.Control=f.Class.extend({defaultActiveArguments:{duration:"fast",completeCallback:b.noop},initialize:function(a,c){var d,e,g,h=this;h.params={},b.extend(h,c||{}),h.id=a,h.selector="#customize-control-"+a.replace(/\]/g,"").replace(/\[/g,"-"),h.templateSelector="customize-control-"+h.params.type+"-content",h.container=b(h.params.content?h.params.content:h.selector),h.deferred={embedded:new b.Deferred},h.section=new f.Value,h.priority=new f.Value,h.active=new f.Value,h.activeArgumentsQueue=[],h.notifications=new f.Values({defaultConstructor:f.Notification}),h.elements=[],d=h.container.find("[data-customize-setting-link]"),e={},d.each(function(){var a,c=b(this);if(c.is(":radio")){if(a=c.prop("name"),e[a])return;e[a]=!0,c=d.filter('[name="'+a+'"]')}f(c.data("customizeSettingLink"),function(a){var b=new f.Element(c);h.elements.push(b),b.sync(a),b.set(a())})}),h.active.bind(function(a){var c=h.activeArgumentsQueue.shift();c=b.extend({},h.defaultActiveArguments,c),h.onChangeActive(a,c)}),h.section.set(h.params.section),h.priority.set(isNaN(h.params.priority)?10:h.params.priority),h.active.set(h.params.active),f.utils.bubbleChildValueChanges(h,["section","priority","active"]),g=b.map(h.params.settings,function(a){return a}),0===g.length?(h.setting=null,h.settings={},h.embed()):f.apply(f,g.concat(function(){var a;h.settings={};for(a in h.params.settings)h.settings[a]=f(h.params.settings[a]);h.setting=h.settings["default"]||null,_.each(h.settings,function(a){a.notifications.bind("add",function(b){var c,d,e;d=a.id+":"+b.code,e=_.extend({},b,{setting:a.id}),c=new f.Notification(d,e),h.notifications.add(c.code,c)}),a.notifications.bind("remove",function(b){h.notifications.remove(a.id+":"+b.code)})}),h.embed()})),h.deferred.embedded.done(function(){var a=_.debounce(function(){h.renderNotifications()});h.notifications.bind("add",function(b){wp.a11y.speak(b.message,"assertive"),a()}),h.notifications.bind("remove",a),h.renderNotifications(),h.ready()})},embed:function(){var a,b=this;a=function(a){var c;a&&f.section(a,function(a){a.deferred.embedded.done(function(){c=a.contentContainer.is("ul")?a.contentContainer:a.contentContainer.find("ul:first"),b.container.parent().is(c)||(c.append(b.container),b.renderContent()),b.deferred.embedded.resolve()})})},b.section.bind(a),a(b.section.get())},ready:function(){},getNotificationsContainerElement:function(){var a,c,d=this;return c=d.container.find(".customize-control-notifications-container:first"),c.length?c:(c=b('<div 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a,c,d=this,e=!1;a=d.getNotificationsContainerElement(),a&&a.length&&(c=[],d.notifications.each(function(a){c.push(a),"error"===a.type&&(e=!0)}),0===c.length?a.stop().slideUp("fast"):a.stop().slideDown("fast",null,function(){b(this).css("height","auto")}),d.notificationsTemplate||(d.notificationsTemplate=wp.template("customize-control-notifications")),d.container.toggleClass("has-notifications",0!==c.length),d.container.toggleClass("has-error",e),a.empty().append(b.trim(d.notificationsTemplate({notifications:c,altNotice:Boolean(d.altNotice)}))))},expand:function(a){f.section(this.section()).expand(a)},focus:d,onChangeActive:function(a,c){return c.unchanged?void(c.completeCallback&&c.completeCallback()):void(b.contains(document,this.container[0])?a?this.container.slideDown(c.duration,c.completeCallback):this.container.slideUp(c.duration,c.completeCallback):(this.container.toggle(a),c.completeCallback&&c.completeCallback()))},toggle:function(a){return this.onChangeActive(a,this.defaultActiveArguments)},activate:c.prototype.activate,deactivate:c.prototype.deactivate,_toggleActive:c.prototype._toggleActive,dropdownInit:function(){var a=this,b=this.container.find(".dropdown-status"),c=this.params,d=!1,e=function(a){"string"==typeof a&&c.statuses&&c.statuses[a]?b.html(c.statuses[a]).show():b.hide()};this.container.on("click keydown",".dropdown",function(b){f.utils.isKeydownButNotEnterEvent(b)||(b.preventDefault(),d||a.container.toggleClass("open"),a.container.hasClass("open")&&a.container.parent().parent().find("li.library-selected").focus(),d=!0,setTimeout(function(){d=!1},400))}),this.setting.bind(e),e(this.setting())},renderContent:function(){var a,c=this;0!==b("#tmpl-"+c.templateSelector).length&&(a=wp.template(c.templateSelector),a&&c.container&&c.container.html(a(c.params)))}}),f.ColorControl=f.Control.extend({ready:function(){var a=this,b=this.container.find(".color-picker-hex");b.val(a.setting()).wpColorPicker({change:function(){a.setting.set(b.wpColorPicker("color"))},clear:function(){a.setting.set("")}}),this.setting.bind(function(a){b.val(a),b.wpColorPicker("color",a)})}}),f.MediaControl=f.Control.extend({ready:function(){function a(a){var d=b.Deferred();c.extended(f.UploadControl)?d.resolve():(a=parseInt(a,10),_.isNaN(a)||0>=a?(delete c.params.attachment,d.resolve()):c.params.attachment&&c.params.attachment.id===a&&d.resolve()),"pending"===d.state()&&wp.media.attachment(a).fetch().done(function(){c.params.attachment=this.attributes,d.resolve(),wp.customize.previewer.send(c.setting.id+"-attachment-data",this.attributes)}),d.done(function(){c.renderContent()})}var c=this;_.bindAll(c,"restoreDefault","removeFile","openFrame","select","pausePlayer"),c.container.on("click keydown",".upload-button",c.openFrame),c.container.on("click keydown",".upload-button",c.pausePlayer),c.container.on("click 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wp.media.controller.Library({title:this.params.button_labels.frame_title,library:wp.media.query({type:this.params.mime_type}),multiple:!1,date:!1})]}),this.frame.on("select",this.select)},select:function(){var a,b=this.frame.state().get("selection").first().toJSON(),c=window._wpmejsSettings||{};this.params.attachment=b,this.setting(b.id),a=this.container.find("audio, video").get(0),a?this.player=new MediaElementPlayer(a,c):this.cleanupPlayer()},restoreDefault:function(a){f.utils.isKeydownButNotEnterEvent(a)||(a.preventDefault(),this.params.attachment=this.params.defaultAttachment,this.setting(this.params.defaultAttachment.url))},removeFile:function(a){f.utils.isKeydownButNotEnterEvent(a)||(a.preventDefault(),this.params.attachment={},this.setting(""),this.renderContent())}}),f.UploadControl=f.MediaControl.extend({select:function(){var a,b=this.frame.state().get("selection").first().toJSON(),c=window._wpmejsSettings||{};this.params.attachment=b,this.setting(b.url),a=this.container.find("audio, video").get(0),a?this.player=new MediaElementPlayer(a,c):this.cleanupPlayer()},success:function(){},removerVisibility:function(){}}),f.ImageControl=f.UploadControl.extend({thumbnailSrc:function(){}}),f.BackgroundControl=f.UploadControl.extend({ready:function(){f.UploadControl.prototype.ready.apply(this,arguments)},select:function(){f.UploadControl.prototype.select.apply(this,arguments),wp.ajax.post("custom-background-add",{nonce:_wpCustomizeBackground.nonces.add,wp_customize:"on",theme:f.settings.theme.stylesheet,attachment_id:this.params.attachment.id})}}),f.CroppedImageControl=f.MediaControl.extend({openFrame:function(a){f.utils.isKeydownButNotEnterEvent(a)||(this.initFrame(),this.frame.setState("library").open())},initFrame:function(){var a=_wpMediaViewsL10n;this.frame=wp.media({button:{text:a.select,close:!1},states:[new wp.media.controller.Library({title:this.params.button_labels.frame_title,library:wp.media.query({type:"image"}),multiple:!1,date:!1,priority:20,suggestedWidth:this.params.width,suggestedHeight:this.params.height}),new wp.media.controller.CustomizeImageCropper({imgSelectOptions:this.calculateImageSelectOptions,control:this})]}),this.frame.on("select",this.onSelect,this),this.frame.on("cropped",this.onCropped,this),this.frame.on("skippedcrop",this.onSkippedCrop,this)},onSelect:function(){var a=this.frame.state().get("selection").first().toJSON();this.params.width!==a.width||this.params.height!==a.height||this.params.flex_width||this.params.flex_height?this.frame.setState("cropper"):(this.setImageFromAttachment(a),this.frame.close())},onCropped:function(a){this.setImageFromAttachment(a)},calculateImageSelectOptions:function(a,b){var c,d,e,f=b.get("control"),g=!!parseInt(f.params.flex_width,10),h=!!parseInt(f.params.flex_height,10),i=a.get("width"),j=a.get("height"),k=parseInt(f.params.width,10),l=parseInt(f.params.height,10),m=k/l,n=k,o=l;return b.set("canSkipCrop",!f.mustBeCropped(g,h,k,l,i,j)),i/j>m?(l=j,k=l*m):(k=i,l=k/m),c=(i-k)/2,d=(j-l)/2,e={handles:!0,keys:!0,instance:!0,persistent:!0,imageWidth:i,imageHeight:j,minWidth:n>k?k:n,minHeight:o>l?l:o,x1:c,y1:d,x2:k+c,y2:l+d},h===!1&&g===!1&&(e.aspectRatio=k+":"+l),!0===h&&(delete e.minHeight,e.maxWidth=i),!0===g&&(delete e.minWidth,e.maxHeight=j),e},mustBeCropped:function(a,b,c,d,e,f){return!0===a&&!0===b?!1:!0===a&&d===f?!1:!0===b&&c===e?!1:c===e&&d===f?!1:!(c>=e)},onSkippedCrop:function(){var a=this.frame.state().get("selection").first().toJSON();this.setImageFromAttachment(a)},setImageFromAttachment:function(a){this.params.attachment=a,this.setting(a.id)}}),f.SiteIconControl=f.CroppedImageControl.extend({initFrame:function(){var a=_wpMediaViewsL10n;this.frame=wp.media({button:{text:a.select,close:!1},states:[new wp.media.controller.Library({title:this.params.button_labels.frame_title,library:wp.media.query({type:"image"}),multiple:!1,date:!1,priority:20,suggestedWidth:this.params.width,suggestedHeight:this.params.height}),new wp.media.controller.SiteIconCropper({imgSelectOptions:this.calculateImageSelectOptions,control:this})]}),this.frame.on("select",this.onSelect,this),this.frame.on("cropped",this.onCropped,this),this.frame.on("skippedcrop",this.onSkippedCrop,this)},onSelect:function(){var a=this.frame.state().get("selection").first().toJSON(),b=this;this.params.width!==a.width||this.params.height!==a.height||this.params.flex_width||this.params.flex_height?this.frame.setState("cropper"):wp.ajax.post("crop-image",{nonce:a.nonces.edit,id:a.id,context:"site-icon",cropDetails:{x1:0,y1:0,width:this.params.width,height:this.params.height,dst_width:this.params.width,dst_height:this.params.height}}).done(function(a){b.setImageFromAttachment(a),b.frame.close()}).fail(function(){b.frame.trigger("content:error:crop")})},setImageFromAttachment:function(a){var c,d=["site_icon-32","thumbnail","full"];_.each(d,function(b){c||_.isUndefined(a.sizes[b])||(c=a.sizes[b])}),this.params.attachment=a,this.setting(a.id),b('link[sizes="32x32"]').attr("href",c.url)},removeFile:function(a){f.utils.isKeydownButNotEnterEvent(a)||(a.preventDefault(),this.params.attachment={},this.setting(""),this.renderContent(),b('link[rel="icon"]').attr("href",""))}}),f.HeaderControl=f.Control.extend({ready:function(){this.btnRemove=b("#customize-control-header_image .actions .remove"),this.btnNew=b("#customize-control-header_image .actions .new"),_.bindAll(this,"openMedia","removeImage"),this.btnNew.on("click",this.openMedia),this.btnRemove.on("click",this.removeImage),f.HeaderTool.currentHeader=this.getInitialHeaderImage(),new f.HeaderTool.CurrentView({model:f.HeaderTool.currentHeader,el:"#customize-control-header_image .current .container"}),new f.HeaderTool.ChoiceListView({collection:f.HeaderTool.UploadsList=new f.HeaderTool.ChoiceList,el:"#customize-control-header_image .choices .uploaded .list"}),new f.HeaderTool.ChoiceListView({collection:f.HeaderTool.DefaultsList=new f.HeaderTool.DefaultsList,el:"#customize-control-header_image .choices .default .list"}),f.HeaderTool.combinedList=f.HeaderTool.CombinedList=new f.HeaderTool.CombinedList([f.HeaderTool.UploadsList,f.HeaderTool.DefaultsList]),wp.media.controller.Cropper.prototype.defaults.doCropArgs.wp_customize="on",wp.media.controller.Cropper.prototype.defaults.doCropArgs.theme=f.settings.theme.stylesheet},getInitialHeaderImage:function(){if(!f.get().header_image||!f.get().header_image_data||_.contains(["remove-header","random-default-image","random-uploaded-image"],f.get().header_image))return new f.HeaderTool.ImageModel;var a=_.find(_wpCustomizeHeader.uploads,function(a){return a.attachment_id===f.get().header_image_data.attachment_id});return a||(a={url:f.get().header_image,thumbnail_url:f.get().header_image,attachment_id:f.get().header_image_data.attachment_id}),new f.HeaderTool.ImageModel({header:a,choice:a.url.split("/").pop()})},calculateImageSelectOptions:function(a,b){var c,d,e,g,h,i,j=parseInt(_wpCustomizeHeader.data.width,10),k=parseInt(_wpCustomizeHeader.data.height,10),l=!!parseInt(_wpCustomizeHeader.data["flex-width"],10),m=!!parseInt(_wpCustomizeHeader.data["flex-height"],10);return h=a.get("width"),g=a.get("height"),this.headerImage=new f.HeaderTool.ImageModel,this.headerImage.set({themeWidth:j,themeHeight:k,themeFlexWidth:l,themeFlexHeight:m,imageWidth:h,imageHeight:g}),b.set("canSkipCrop",!this.headerImage.shouldBeCropped()),c=j/k,d=h,e=g,d/e>c?(k=e,j=k*c):(j=d,k=j/c),i={handles:!0,keys:!0,instance:!0,persistent:!0,imageWidth:h,imageHeight:g,x1:0,y1:0,x2:j,y2:k},m===!1&&l===!1&&(i.aspectRatio=j+":"+k),m===!1&&(i.maxHeight=k),l===!1&&(i.maxWidth=j),i},openMedia:function(a){var b=_wpMediaViewsL10n;a.preventDefault(),this.frame=wp.media({button:{text:b.selectAndCrop,close:!1},states:[new wp.media.controller.Library({title:b.chooseImage,library:wp.media.query({type:"image"}),multiple:!1,date:!1,priority:20,suggestedWidth:_wpCustomizeHeader.data.width,suggestedHeight:_wpCustomizeHeader.data.height}),new wp.media.controller.Cropper({imgSelectOptions:this.calculateImageSelectOptions})]}),this.frame.on("select",this.onSelect,this),this.frame.on("cropped",this.onCropped,this),this.frame.on("skippedcrop",this.onSkippedCrop,this),this.frame.open()},onSelect:function(){this.frame.setState("cropper")},onCropped:function(a){var b=a.url,c=a.attachment_id,d=a.width,e=a.height;this.setImageFromURL(b,c,d,e)},onSkippedCrop:function(a){var b=a.get("url"),c=a.get("width"),d=a.get("height");this.setImageFromURL(b,a.id,c,d)},setImageFromURL:function(a,b,c,d){var e,g={};g.url=a,g.thumbnail_url=a,g.timestamp=_.now(),b&&(g.attachment_id=b),c&&(g.width=c),d&&(g.height=d),e=new f.HeaderTool.ImageModel({header:g,choice:a.split("/").pop()}),f.HeaderTool.UploadsList.add(e),f.HeaderTool.currentHeader.set(e.toJSON()),e.save(),e.importImage()},removeImage:function(){f.HeaderTool.currentHeader.trigger("hide"),f.HeaderTool.CombinedList.trigger("control:removeImage")}}),f.ThemeControl=f.Control.extend({touchDrag:!1,isRendered:!1,renderContent:function(){var a=this,b=arguments;f.section(a.section(),function(c){c.expanded()?(f.Control.prototype.renderContent.apply(a,b),a.isRendered=!0):c.expanded.bind(function(c){c&&!a.isRendered&&(f.Control.prototype.renderContent.apply(a,b),a.isRendered=!0)})})},ready:function(){var a=this;a.container.on("touchmove",".theme",function(){
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f.Values({defaultConstructor:f.Panel}),f.PreviewFrame=f.Messenger.extend({sensitivity:2e3,initialize:function(a,c){var d=b.Deferred();d.promise(this),this.container=a.container,this.signature=a.signature,b.extend(a,{channel:f.PreviewFrame.uuid()}),f.Messenger.prototype.initialize.call(this,a,c),this.add("previewUrl",a.previewUrl),this.query=b.extend(a.query||{},{customize_messenger_channel:this.channel()}),this.run(d)},run:function(a){var c=this,d=!1,e=!1;this._ready&&this.unbind("ready",this._ready),this._ready=function(){e=!0,d&&a.resolveWith(c)},this.bind("ready",this._ready),this.bind("ready",function(a){if(this.container.addClass("iframe-ready"),a){var b={panel:a.activePanels,section:a.activeSections,control:a.activeControls};_(b).each(function(a,b){f[b].each(function(c,d){var 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c=this,d=c.contentContainer,e=d.closest(".wp-full-overlay"),g=d.closest(".wp-full-overlay-sidebar-content"),h=c.headContainer.find(".accordion-section-title"),i=d.find(".customize-panel-back");a&&!d.hasClass("current-panel")?(f.section.each(function(a){c.id!==a.panel()&&a.collapse({duration:0})}),f.panel.each(function(a){c!==a&&a.collapse({duration:0})}),c._animateChangeExpanded(function(){h.attr("tabindex","-1"),i.attr("tabindex","0"),i.focus(),d.css("top",""),g.scrollTop(0),b.completeCallback&&b.completeCallback()}),e.addClass("in-sub-panel"),d.addClass("current-panel")):!a&&d.hasClass("current-panel")&&(c._animateChangeExpanded(function(){h.attr("tabindex","0"),i.attr("tabindex","-1"),h.focus(),d.css("top",""),b.completeCallback&&b.completeCallback()}),e.removeClass("in-sub-panel"),d.removeClass("current-panel"))},renderContent:function(){var a,c=this;a=0!==b("#tmpl-"+c.templateSelector+"-content").length?wp.template(c.templateSelector+"-content"):wp.template("customize-panel-default-content"),a&&c.headContainer&&c.contentContainer.html(a(c.params))}}),f.Control=f.Class.extend({defaultActiveArguments:{duration:"fast",completeCallback:b.noop},initialize:function(a,c){var d,e,g,h=this;h.params={},b.extend(h,c||{}),h.id=a,h.selector="#customize-control-"+a.replace(/\]/g,"").replace(/\[/g,"-"),h.templateSelector="customize-control-"+h.params.type+"-content",h.container=b(h.params.content?h.params.content:h.selector),h.deferred={embedded:new b.Deferred},h.section=new f.Value,h.priority=new f.Value,h.active=new f.Value,h.activeArgumentsQueue=[],h.notifications=new f.Values({defaultConstructor:f.Notification}),h.elements=[],d=h.container.find("[data-customize-setting-link]"),e={},d.each(function(){var a,c=b(this);if(c.is(":radio")){if(a=c.prop("name"),e[a])return;e[a]=!0,c=d.filter('[name="'+a+'"]')}f(c.data("customizeSettingLink"),function(a){var b=new f.Element(c);h.elements.push(b),b.sync(a),b.set(a())})}),h.active.bind(function(a){var c=h.activeArgumentsQueue.shift();c=b.extend({},h.defaultActiveArguments,c),h.onChangeActive(a,c)}),h.section.set(h.params.section),h.priority.set(isNaN(h.params.priority)?10:h.params.priority),h.active.set(h.params.active),f.utils.bubbleChildValueChanges(h,["section","priority","active"]),g=b.map(h.params.settings,function(a){return a}),0===g.length?(h.setting=null,h.settings={},h.embed()):f.apply(f,g.concat(function(){var a;h.settings={};for(a in h.params.settings)h.settings[a]=f(h.params.settings[a]);h.setting=h.settings["default"]||null,_.each(h.settings,function(a){a.notifications.bind("add",function(b){var c,d,e;d=a.id+":"+b.code,e=_.extend({},b,{setting:a.id}),c=new f.Notification(d,e),h.notifications.add(c.code,c)}),a.notifications.bind("remove",function(b){h.notifications.remove(a.id+":"+b.code)})}),h.embed()})),h.deferred.embedded.done(function(){var a=_.debounce(function(){h.renderNotifications()});h.notifications.bind("add",function(b){wp.a11y.speak(b.message,"assertive"),a()}),h.notifications.bind("remove",a),h.renderNotifications(),h.ready()})},embed:function(){var a,b=this;a=function(a){var c;a&&f.section(a,function(a){a.deferred.embedded.done(function(){c=a.contentContainer.is("ul")?a.contentContainer:a.contentContainer.find("ul:first"),b.container.parent().is(c)||(c.append(b.container),b.renderContent()),b.deferred.embedded.resolve()})})},b.section.bind(a),a(b.section.get())},ready:function(){},getNotificationsContainerElement:function(){var a,c,d=this;return c=d.container.find(".customize-control-notifications-container:first"),c.length?c:(c=b('<div 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a,c,d=this,e=!1;a=d.getNotificationsContainerElement(),a&&a.length&&(c=[],d.notifications.each(function(a){c.push(a),"error"===a.type&&(e=!0)}),0===c.length?a.stop().slideUp("fast"):a.stop().slideDown("fast",null,function(){b(this).css("height","auto")}),d.notificationsTemplate||(d.notificationsTemplate=wp.template("customize-control-notifications")),d.container.toggleClass("has-notifications",0!==c.length),d.container.toggleClass("has-error",e),a.empty().append(b.trim(d.notificationsTemplate({notifications:c,altNotice:Boolean(d.altNotice)}))))},expand:function(a){f.section(this.section()).expand(a)},focus:d,onChangeActive:function(a,c){return c.unchanged?void(c.completeCallback&&c.completeCallback()):void(b.contains(document,this.container[0])?a?this.container.slideDown(c.duration,c.completeCallback):this.container.slideUp(c.duration,c.completeCallback):(this.container.toggle(a),c.completeCallback&&c.completeCallback()))},toggle:function(a){return this.onChangeActive(a,this.defaultActiveArguments)},activate:c.prototype.activate,deactivate:c.prototype.deactivate,_toggleActive:c.prototype._toggleActive,dropdownInit:function(){var a=this,b=this.container.find(".dropdown-status"),c=this.params,d=!1,e=function(a){"string"==typeof a&&c.statuses&&c.statuses[a]?b.html(c.statuses[a]).show():b.hide()};this.container.on("click keydown",".dropdown",function(b){f.utils.isKeydownButNotEnterEvent(b)||(b.preventDefault(),d||a.container.toggleClass("open"),a.container.hasClass("open")&&a.container.parent().parent().find("li.library-selected").focus(),d=!0,setTimeout(function(){d=!1},400))}),this.setting.bind(e),e(this.setting())},renderContent:function(){var a,c=this;0!==b("#tmpl-"+c.templateSelector).length&&(a=wp.template(c.templateSelector),a&&c.container&&c.container.html(a(c.params)))}}),f.ColorControl=f.Control.extend({ready:function(){var a=this,b=this.container.find(".color-picker-hex");b.val(a.setting()).wpColorPicker({change:function(){a.setting.set(b.wpColorPicker("color"))},clear:function(){a.setting.set("")}}),this.setting.bind(function(a){b.val(a),b.wpColorPicker("color",a)})}}),f.MediaControl=f.Control.extend({ready:function(){function a(a){var d=b.Deferred();c.extended(f.UploadControl)?d.resolve():(a=parseInt(a,10),_.isNaN(a)||0>=a?(delete c.params.attachment,d.resolve()):c.params.attachment&&c.params.attachment.id===a&&d.resolve()),"pending"===d.state()&&wp.media.attachment(a).fetch().done(function(){c.params.attachment=this.attributes,d.resolve(),wp.customize.previewer.send(c.setting.id+"-attachment-data",this.attributes)}),d.done(function(){c.renderContent()})}var c=this;_.bindAll(c,"restoreDefault","removeFile","openFrame","select","pausePlayer"),c.container.on("click keydown",".upload-button",c.openFrame),c.container.on("click keydown",".upload-button",c.pausePlayer),c.container.on("click 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a,b=this.frame.state().get("selection").first().toJSON(),c=window._wpmejsSettings||{};this.params.attachment=b,this.setting(b.url),a=this.container.find("audio, video").get(0),a?this.player=new MediaElementPlayer(a,c):this.cleanupPlayer()},success:function(){},removerVisibility:function(){}}),f.ImageControl=f.UploadControl.extend({thumbnailSrc:function(){}}),f.BackgroundControl=f.UploadControl.extend({ready:function(){f.UploadControl.prototype.ready.apply(this,arguments)},select:function(){f.UploadControl.prototype.select.apply(this,arguments),wp.ajax.post("custom-background-add",{nonce:_wpCustomizeBackground.nonces.add,wp_customize:"on",customize_theme:f.settings.theme.stylesheet,attachment_id:this.params.attachment.id})}}),f.CroppedImageControl=f.MediaControl.extend({openFrame:function(a){f.utils.isKeydownButNotEnterEvent(a)||(this.initFrame(),this.frame.setState("library").open())},initFrame:function(){var a=_wpMediaViewsL10n;this.frame=wp.media({button:{text:a.select,close:!1},states:[new wp.media.controller.Library({title:this.params.button_labels.frame_title,library:wp.media.query({type:"image"}),multiple:!1,date:!1,priority:20,suggestedWidth:this.params.width,suggestedHeight:this.params.height}),new wp.media.controller.CustomizeImageCropper({imgSelectOptions:this.calculateImageSelectOptions,control:this})]}),this.frame.on("select",this.onSelect,this),this.frame.on("cropped",this.onCropped,this),this.frame.on("skippedcrop",this.onSkippedCrop,this)},onSelect:function(){var a=this.frame.state().get("selection").first().toJSON();this.params.width!==a.width||this.params.height!==a.height||this.params.flex_width||this.params.flex_height?this.frame.setState("cropper"):(this.setImageFromAttachment(a),this.frame.close())},onCropped:function(a){this.setImageFromAttachment(a)},calculateImageSelectOptions:function(a,b){var c,d,e,f=b.get("control"),g=!!parseInt(f.params.flex_width,10),h=!!parseInt(f.params.flex_height,10),i=a.get("width"),j=a.get("height"),k=parseInt(f.params.width,10),l=parseInt(f.params.height,10),m=k/l,n=k,o=l;return b.set("canSkipCrop",!f.mustBeCropped(g,h,k,l,i,j)),i/j>m?(l=j,k=l*m):(k=i,l=k/m),c=(i-k)/2,d=(j-l)/2,e={handles:!0,keys:!0,instance:!0,persistent:!0,imageWidth:i,imageHeight:j,minWidth:n>k?k:n,minHeight:o>l?l:o,x1:c,y1:d,x2:k+c,y2:l+d},h===!1&&g===!1&&(e.aspectRatio=k+":"+l),!0===h&&(delete e.minHeight,e.maxWidth=i),!0===g&&(delete e.minWidth,e.maxHeight=j),e},mustBeCropped:function(a,b,c,d,e,f){return!0===a&&!0===b?!1:!0===a&&d===f?!1:!0===b&&c===e?!1:c===e&&d===f?!1:!(c>=e)},onSkippedCrop:function(){var a=this.frame.state().get("selection").first().toJSON();this.setImageFromAttachment(a)},setImageFromAttachment:function(a){this.params.attachment=a,this.setting(a.id)}}),f.SiteIconControl=f.CroppedImageControl.extend({initFrame:function(){var a=_wpMediaViewsL10n;this.frame=wp.media({button:{text:a.select,close:!1},states:[new wp.media.controller.Library({title:this.params.button_labels.frame_title,library:wp.media.query({type:"image"}),multiple:!1,date:!1,priority:20,suggestedWidth:this.params.width,suggestedHeight:this.params.height}),new wp.media.controller.SiteIconCropper({imgSelectOptions:this.calculateImageSelectOptions,control:this})]}),this.frame.on("select",this.onSelect,this),this.frame.on("cropped",this.onCropped,this),this.frame.on("skippedcrop",this.onSkippedCrop,this)},onSelect:function(){var a=this.frame.state().get("selection").first().toJSON(),b=this;this.params.width!==a.width||this.params.height!==a.height||this.params.flex_width||this.params.flex_height?this.frame.setState("cropper"):wp.ajax.post("crop-image",{nonce:a.nonces.edit,id:a.id,context:"site-icon",cropDetails:{x1:0,y1:0,width:this.params.width,height:this.params.height,dst_width:this.params.width,dst_height:this.params.height}}).done(function(a){b.setImageFromAttachment(a),b.frame.close()}).fail(function(){b.frame.trigger("content:error:crop")})},setImageFromAttachment:function(a){var c,d=["site_icon-32","thumbnail","full"];_.each(d,function(b){c||_.isUndefined(a.sizes[b])||(c=a.sizes[b])}),this.params.attachment=a,this.setting(a.id),b('link[sizes="32x32"]').attr("href",c.url)},removeFile:function(a){f.utils.isKeydownButNotEnterEvent(a)||(a.preventDefault(),this.params.attachment={},this.setting(""),this.renderContent(),b('link[rel="icon"]').attr("href",""))}}),f.HeaderControl=f.Control.extend({ready:function(){this.btnRemove=b("#customize-control-header_image .actions .remove"),this.btnNew=b("#customize-control-header_image .actions .new"),_.bindAll(this,"openMedia","removeImage"),this.btnNew.on("click",this.openMedia),this.btnRemove.on("click",this.removeImage),f.HeaderTool.currentHeader=this.getInitialHeaderImage(),new f.HeaderTool.CurrentView({model:f.HeaderTool.currentHeader,el:"#customize-control-header_image .current .container"}),new f.HeaderTool.ChoiceListView({collection:f.HeaderTool.UploadsList=new f.HeaderTool.ChoiceList,el:"#customize-control-header_image .choices .uploaded .list"}),new f.HeaderTool.ChoiceListView({collection:f.HeaderTool.DefaultsList=new f.HeaderTool.DefaultsList,el:"#customize-control-header_image .choices .default .list"}),f.HeaderTool.combinedList=f.HeaderTool.CombinedList=new f.HeaderTool.CombinedList([f.HeaderTool.UploadsList,f.HeaderTool.DefaultsList]),wp.media.controller.Cropper.prototype.defaults.doCropArgs.wp_customize="on",wp.media.controller.Cropper.prototype.defaults.doCropArgs.customize_theme=f.settings.theme.stylesheet},getInitialHeaderImage:function(){if(!f.get().header_image||!f.get().header_image_data||_.contains(["remove-header","random-default-image","random-uploaded-image"],f.get().header_image))return new f.HeaderTool.ImageModel;var a=_.find(_wpCustomizeHeader.uploads,function(a){return a.attachment_id===f.get().header_image_data.attachment_id});return a||(a={url:f.get().header_image,
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b=_wpMediaViewsL10n;a.preventDefault(),this.frame=wp.media({button:{text:b.selectAndCrop,close:!1},states:[new wp.media.controller.Library({title:b.chooseImage,library:wp.media.query({type:"image"}),multiple:!1,date:!1,priority:20,suggestedWidth:_wpCustomizeHeader.data.width,suggestedHeight:_wpCustomizeHeader.data.height}),new wp.media.controller.Cropper({imgSelectOptions:this.calculateImageSelectOptions})]}),this.frame.on("select",this.onSelect,this),this.frame.on("cropped",this.onCropped,this),this.frame.on("skippedcrop",this.onSkippedCrop,this),this.frame.open()},onSelect:function(){this.frame.setState("cropper")},onCropped:function(a){var b=a.url,c=a.attachment_id,d=a.width,e=a.height;this.setImageFromURL(b,c,d,e)},onSkippedCrop:function(a){var b=a.get("url"),c=a.get("width"),d=a.get("height");this.setImageFromURL(b,a.id,c,d)},setImageFromURL:function(a,b,c,d){var e,g={};g.url=a,g.thumbnail_url=a,g.timestamp=_.now(),b&&(g.attachment_id=b),c&&(g.width=c),d&&(g.height=d),e=new f.HeaderTool.ImageModel({header:g,choice:a.split("/").pop()}),f.HeaderTool.UploadsList.add(e),f.HeaderTool.currentHeader.set(e.toJSON()),e.save(),e.importImage()},removeImage:function(){f.HeaderTool.currentHeader.trigger("hide"),f.HeaderTool.CombinedList.trigger("control:removeImage")}}),f.ThemeControl=f.Control.extend({touchDrag:!1,isRendered:!1,renderContent:function(){var a=this,b=arguments;f.section(a.section(),function(c){c.expanded()?(f.Control.prototype.renderContent.apply(a,b),a.isRendered=!0):c.expanded.bind(function(c){c&&!a.isRendered&&(f.Control.prototype.renderContent.apply(a,b),a.isRendered=!0)})})},ready:function(){var a=this;a.container.on("touchmove",".theme",function(){a.touchDrag=!0}),a.container.on("click keydown touchend",".theme",function(c){return f.utils.isKeydownButNotEnterEvent(c)?void 0:a.touchDrag===!0?a.touchDrag=!1:void(b(c.target).is(".theme-actions .button")||f.section(a.section()).loadThemePreview(a.params.theme.id))}),a.container.on("click keydown",".theme-actions .theme-details",function(b){f.utils.isKeydownButNotEnterEvent(b)||(b.preventDefault(),f.section(a.section()).showDetails(a.params.theme))}),a.container.on("render-screenshot",function(){var a=b(this).find("img"),c=a.data("src");c&&a.attr("src",c)})},filter:function(a){var b=this,c=b.params.theme.name+" "+b.params.theme.description+" "+b.params.theme.tags+" "+b.params.theme.author;c=c.toLowerCase().replace("-"," "),-1!==c.search(a)?b.activate():b.deactivate()}}),f.defaultConstructor=f.Setting,f.control=new f.Values({defaultConstructor:f.Control}),f.section=new f.Values({defaultConstructor:f.Section}),f.panel=new f.Values({defaultConstructor:f.Panel}),f.PreviewFrame=f.Messenger.extend({sensitivity:null,initialize:function(a,c){var d=b.Deferred();d.promise(this),this.container=a.container,b.extend(a,{channel:f.PreviewFrame.uuid()}),f.Messenger.prototype.initialize.call(this,a,c),this.add("previewUrl",a.previewUrl),this.query=b.extend(a.query||{},{customize_messenger_channel:this.channel()}),this.run(d)},run:function(a){var c,d,e,g=this,h=!1,i=!1,j=null,k="{}"!==g.query.customized;g._ready&&g.unbind("ready",g._ready),g._ready=function(b){i=!0,j=b,g.container.addClass("iframe-ready"),b&&h&&a.resolveWith(g,[b])},g.bind("ready",g._ready),c=document.createElement("a"),c.href=g.previewUrl(),d=_.extend(f.utils.parseQueryString(c.search.substr(1)),{customize_changeset_uuid:g.query.customize_changeset_uuid,customize_theme:g.query.customize_theme,customize_messenger_channel:g.query.customize_messenger_channel}),c.search=b.param(d),g.iframe=b("<iframe />",{title:f.l10n.previewIframeTitle,name:"customize-"+g.channel()}),g.iframe.attr("onmousewheel",""),k?g.iframe.attr("data-src",c.href):g.iframe.attr("src",c.href),g.iframe.appendTo(g.container),g.targetWindow(g.iframe[0].contentWindow),k&&(e=b("<form>",{action:c.href,target:g.iframe.attr("name"),method:"post",hidden:"hidden"}),e.append(b("<input>",{type:"hidden",name:"_method",value:"GET"})),_.each(g.query,function(a,c){e.append(b("<input>",{type:"hidden",name:c,value:a}))}),g.container.append(e),e.submit(),e.remove()),g.bind("iframe-loading-error",function(b){return g.iframe.remove(),0===b?void g.login(a):-1===b?void a.rejectWith(g,["cheatin"]):void a.rejectWith(g,["request failure"])}),g.iframe.one("load",function(){h=!0,i?a.resolveWith(g,[j]):setTimeout(function(){a.rejectWith(g,["ready timeout"])},g.sensitivity)})},login:function(a){var c,d=this;return c=function(){a.rejectWith(d,["logged out"])},this.triedLogin?c():void b.get(f.settings.url.ajax,{action:"logged-in"}).fail(c).done(function(e){var g;"1"!==e&&c(),g=b("<iframe />",{src:d.previewUrl(),title:f.l10n.previewIframeTitle}).hide(),g.appendTo(d.container),g.on("load",function(){d.triedLogin=!0,g.remove(),d.run(a)})})},destroy:function(){f.Messenger.prototype.destroy.call(this),this.iframe&&this.iframe.remove(),delete this.iframe,delete this.targetWindow}}),function(){var a=0;f.PreviewFrame.uuid=function(){return"preview-"+String(a++)}}(),f.setDocumentTitle=function(a){var b,c;b=f.settings.documentTitleTmpl,c=b.replace("%s",a),document.title=c,f.trigger("title",c)},f.Previewer=f.Messenger.extend({refreshBuffer:null,initialize:function(a,c){var d=this,e=document.createElement("a");b.extend(d,c||{}),d.deferred={active:b.Deferred()},d.refresh=_.debounce(function(a){return function(){var b,c;b=function(){return 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e=_.isUndefined(f.settings[b+"s"][d]);e&&_.isUndefined(a[d])||(a[d]?c.activate():c.deactivate())})}),a.settingValidities&&f._handleSettingValidities({settingValidities:a.settingValidities,focusInvalidControl:!1})},keepPreviewAlive:function(){var a,b,c,d,e=this;d=function(){b=setTimeout(c,f.settings.timeouts.keepAliveCheck)},a=function(){f.state("previewerAlive").set(!0),clearTimeout(b),d()},c=function(){f.state("previewerAlive").set(!1)},d(),e.bind("ready",a),e.bind("keep-alive",a)},query:function(){},abort:function(){this.loading&&(this.loading.destroy(),delete this.loading)},refresh:function(){var a=this;a.send("loading-initiated"),a.abort(),a.loading=new f.PreviewFrame({url:a.url(),previewUrl:a.previewUrl(),query:a.query({excludeCustomizedSaved:!0})||{},container:a.container}),a.loading.done(function(b){var c,d,e=this;c=a.preview,a.preview=e,a.targetWindow(e.targetWindow()),a.channel(e.channel()),d=function(){e.unbind("synced",d),c&&c.destroy(),a.deferred.active.resolve(),delete a.loading},e.bind("synced",d),a.trigger("ready",b)}),a.loading.fail(function(b){a.send("loading-failed"),"logged out"===b&&(a.preview&&(a.preview.destroy(),delete a.preview),a.login().done(a.refresh)),"cheatin"===b&&a.cheatin()})},login:function(){var a,c,d,e=this;return this._login?this._login:(a=b.Deferred(),this._login=a.promise(),c=new f.Messenger({channel:"login",url:f.settings.url.login}),d=b("<iframe />",{src:f.settings.url.login,title:f.l10n.loginIframeTitle}).appendTo(this.container),c.targetWindow(d[0].contentWindow),c.bind("login",function(){var b=e.refreshNonces();b.always(function(){d.remove(),c.destroy(),delete e._login}),b.done(function(){a.resolve()}),b.fail(function(){e.cheatin(),a.reject()})}),this._login)},cheatin:function(){b(document.body).empty().addClass("cheatin").append("<h1>"+f.l10n.cheatin+"</h1><p>"+f.l10n.notAllowed+"</p>")},refreshNonces:function(){var a,c=b.Deferred();return c.promise(),a=wp.ajax.post("customize_refresh_nonces",{wp_customize:"on",customize_theme:f.settings.theme.stylesheet}),a.done(function(a){f.trigger("nonce-refresh",a),c.resolve()}),a.fail(function(){c.reject()}),c}}),f.settingConstructor={},f.controlConstructor={color:f.ColorControl,media:f.MediaControl,upload:f.UploadControl,image:f.ImageControl,cropped_image:f.CroppedImageControl,site_icon:f.SiteIconControl,header:f.HeaderControl,background:f.BackgroundControl,theme:f.ThemeControl},f.panelConstructor={},f.sectionConstructor={themes:f.ThemesSection},f._handleSettingValidities=function(a){var b,c=[],d=!1;_.each(a.settingValidities,function(a,b){var d=f(b);d&&(_.isObject(a)&&_.each(a,function(a,b){var e,g,h=!1;e=new f.Notification(b,_.extend({fromServer:!0},a)),g=d.notifications(e.code),g&&(h=e.type!==g.type||e.message!==g.message||!_.isEqual(e.data,g.data)),h&&d.notifications.remove(b),d.notifications.has(e.code)||d.notifications.add(b,e),c.push(d.id)}),d.notifications.each(function(b){"error"!==b.type||!0!==a&&a[b.code]||d.notifications.remove(b.code)}))}),a.focusInvalidControl&&(b=f.findControlsForSettings(c),_(_.values(b)).find(function(a){return _(a).find(function(a){var b=a.section()&&f.section.has(a.section())&&f.section(a.section()).expanded();return b&&a.expanded&&(b=a.expanded()),b&&(a.focus(),d=!0),d})}),d||_.isEmpty(b)||_.values(b)[0][0].focus())},f.findControlsForSettings=function(a){var b,c={};return _.each(_.unique(a),function(a){var d=f(a);d&&(b=d.findControls(),b&&b.length>0&&(c[a]=b))}),c},f.reflowPaneContents=_.bind(function(){var a,c,d,e=[],g=!1;document.activeElement&&(c=b(document.activeElement)),f.panel.each(function(b){var c=b.sections(),d=_.pluck(c,"headContainer");e.push(b),a=b.contentContainer.is("ul")?b.contentContainer:b.contentContainer.find("ul:first"),f.utils.areElementListsEqual(d,a.children("[id]"))||(_(c).each(function(b){a.append(b.headContainer)}),g=!0)}),f.section.each(function(b){var c=b.controls(),d=_.pluck(c,"container");b.panel()||e.push(b),a=b.contentContainer.is("ul")?b.contentContainer:b.contentContainer.find("ul:first"),f.utils.areElementListsEqual(d,a.children("[id]"))||(_(c).each(function(b){a.append(b.container)}),g=!0)}),e.sort(f.utils.prioritySort),d=_.pluck(e,"headContainer"),a=b("#customize-theme-controls .customize-pane-parent"),f.utils.areElementListsEqual(d,a.children())||(_(e).each(function(b){a.append(b.headContainer)}),g=!0),f.panel.each(function(a){var b=a.active();a.active.callbacks.fireWith(a.active,[b,b])}),f.section.each(function(a){var b=a.active();a.active.callbacks.fireWith(a.active,[b,b])}),g&&c&&c.focus(),f.trigger("pane-contents-reflowed")},f),b(function(){if(f.settings=window._wpCustomizeSettings,f.l10n=window._wpCustomizeControlsL10n,f.settings&&b.support.postMessage&&(b.support.cors||!f.settings.isCrossDomain)){null===f.PreviewFrame.prototype.sensitivity&&(f.PreviewFrame.prototype.sensitivity=f.settings.timeouts.previewFrameSensitivity),null===f.Previewer.prototype.refreshBuffer&&(f.Previewer.prototype.refreshBuffer=f.settings.timeouts.windowRefresh);var a,c=b(document.body),d=c.children(".wp-full-overlay"),e=b("#customize-info .panel-title.site-title"),g=b(".customize-controls-close"),h=b("#save"),i=b("#customize-footer-actions");b("#customize-controls").on("keydown",function(a){var c=13===a.which,d=b(a.target);c&&(d.is("input:not([type=button])")||d.is("select"))&&a.preventDefault()}),b(".customize-info").find("> .accordion-section-title .customize-help-toggle").on("click",function(){var a=b(this).closest(".accordion-section"),c=a.find(".customize-panel-description:first");a.hasClass("cannot-expand")||(a.hasClass("open")?(a.toggleClass("open"),c.slideUp(f.Panel.prototype.defaultExpandedArguments.duration),b(this).attr("aria-expanded",!1)):(c.slideDown(f.Panel.prototype.defaultExpandedArguments.duration),a.toggleClass("open"),b(this).attr("aria-expanded",!0)))}),f.previewer=new f.Previewer({container:"#customize-preview",form:"#customize-controls",previewUrl:f.settings.url.preview,allowedUrls:f.settings.url.allowed},{nonce:f.settings.nonce,query:function(a){var b={wp_customize:"on",customize_theme:f.settings.theme.stylesheet,nonce:this.nonce.preview,customize_changeset_uuid:f.settings.changeset.uuid};return b.customized=JSON.stringify(f.dirtyValues({unsaved:a&&a.excludeCustomizedSaved})),b},save:function(c){function d(a){n[a.id]=!0}var e,g,i,j=this,k=b.Deferred(),l="publish",m=f.state("processing"),n={},o=[];return c&&c.status&&(l=c.status),f.state("saving").get()&&(k.reject("already_saving"),k.promise()),f.state("saving").set(!0),f.bind("change",d),g=function(){var e,g,m={};return f.each(function(a){a.notifications.each(function(b){"error"!==b.type||b.fromServer||(o.push(a.id),m[a.id]||(m[a.id]={}),m[a.id][b.code]=b)})}),i=f.findControlsForSettings(o),_.isEmpty(i)?(g=b.extend(j.query({excludeCustomizedSaved:!1}),{nonce:j.nonce.save,customize_changeset_status:l}),c&&c.date&&(g.customize_changeset_date=c.date),c&&c.title&&(g.customize_changeset_title=c.title),e=wp.ajax.post("customize_save",g),h.prop("disabled",!0),f.trigger("save",e),e.always(function(){f.state("saving").set(!1),h.prop("disabled",!1),f.unbind("change",d)}),e.fail(function(a){"0"===a?a="not_logged_in":"-1"===a&&(a="invalid_nonce"),"invalid_nonce"===a?j.cheatin():"not_logged_in"===a&&(j.preview.iframe.hide(),j.login().done(function(){j.save(),j.preview.iframe.show()})),a.setting_validities&&f._handleSettingValidities({settingValidities:a.setting_validities,focusInvalidControl:!0}),k.rejectWith(j,[a]),f.trigger("error",a)}),void e.done(function(b){j.send("saved",b),f.state("changesetStatus").set(b.changeset_status),"publish"===b.changeset_status&&(f.state("changesetStatus").set(""),f.settings.changeset.uuid=b.next_changeset_uuid,a.send("changeset-uuid",f.settings.changeset.uuid)),b.setting_validities&&f._handleSettingValidities({settingValidities:b.setting_validities,focusInvalidControl:!0}),k.resolveWith(j,[b]),f.trigger("saved",b),_.isEmpty(n)||f.state("saved").set(!1)})):(_.values(i)[0][0].focus(),f.unbind("change",d),k.rejectWith(j,[{setting_invalidities:m}]),f.state("saving").set(!1),k.promise())},0===m()?g():(e=function(){0===m()&&(f.state.unbind("change",e),g())},f.state.bind("change",e)),k.promise()}}),f.previewer.bind("nonce",function(a){b.extend(this.nonce,a)}),f.bind("nonce-refresh",function(a){b.extend(f.settings.nonce,a),b.extend(f.previewer.nonce,a),f.previewer.send("nonce-refresh",a)}),b.each(f.settings.settings,function(a,b){var c,d=f.settingConstructor[b.type]||f.Setting;c=new d(a,b.value,{transport:b.transport,previewer:f.previewer,dirty:!!b.dirty}),f.add(a,c)}),b.each(f.settings.panels,function(a,b){var c,d=f.panelConstructor[b.type]||f.Panel;c=new d(a,{params:b}),f.panel.add(a,c)}),b.each(f.settings.sections,function(a,b){var c,d=f.sectionConstructor[b.type]||f.Section;c=new d(a,{params:b}),f.section.add(a,c)}),b.each(f.settings.controls,function(a,b){var c,d=f.controlConstructor[b.type]||f.Control;c=new d(a,{params:b,previewer:f.previewer}),f.control.add(a,c)}),_.each(["panel","section","control"],function(a){var b=f.settings.autofocus[a];b&&f[a](b,function(a){a.deferred.embedded.done(function(){f.previewer.deferred.active.done(function(){a.focus()})})})}),f.bind("ready",f.reflowPaneContents),b([f.panel,f.section,f.control]).each(function(a,b){var c=_.debounce(f.reflowPaneContents,f.settings.timeouts.reflowPaneContents);b.bind("add",c),b.bind("change",c),b.bind("remove",c)}),function(){var a,d=new f.Values,e=d.create("saved"),i=d.create("saving"),j=d.create("activated"),k=d.create("processing"),l=d.create("paneVisible"),m=d.create("changesetStatus"),n=d.create("previewerAlive");d.bind("change",function(){var a;j()?""===m.get()&&e()?(h.val(f.l10n.saved),g.find(".screen-reader-text").text(f.l10n.close)):(h.val(f.l10n.save),g.find(".screen-reader-text").text(f.l10n.cancel)):(h.val(f.l10n.activate),g.find(".screen-reader-text").text(f.l10n.cancel)),a=!i()&&(!j()||!e()||""!==m()&&"publish"!==m()),h.prop("disabled",!a)}),e(!0),i(!1),j(f.settings.theme.active),k(0),l(!0),n(!0),m(f.settings.changeset.status),f.bind("change",function(){d("saved").set(!1)}),i.bind(function(a){c.toggleClass("saving",a)}),f.bind("saved",function(a){d("saved").set(!0),"publish"===a.changeset_status&&d("activated").set(!0)}),j.bind(function(a){a&&f.trigger("activated")}),a=function(a){var c,d;if(c=document.createElement("a"),c.href=location.href,d=f.utils.parseQueryString(c.search.substr(1)),a){if(d.changeset_uuid===f.settings.changeset.uuid)return;d.changeset_uuid=f.settings.changeset.uuid}else{if(!d.changeset_uuid)return;delete d.changeset_uuid}c.search=b.param(d),history.replaceState({},document.title,c.href)},history.replaceState&&(e.bind(function(b){b||a(!0)}),m.bind(function(b){a(""!==b)})),f.state=d}(),f.previewer.previewUrl()?f.previewer.refresh():f.previewer.previewUrl(f.settings.url.home),h.click(function(a){f.previewer.save(),a.preventDefault()}).keydown(function(a){9!==a.which&&(13===a.which&&f.previewer.save(),a.preventDefault())}),g.keydown(function(a){9!==a.which&&(13===a.which&&this.click(),a.preventDefault())}),b(".collapse-sidebar").on("click",function(){f.state("paneVisible").set(!f.state("paneVisible").get())}),f.state("paneVisible").bind(function(a){d.toggleClass("expanded",a),d.toggleClass("collapsed",!a),a?b(".collapse-sidebar").attr({"aria-expanded":"true","aria-label":f.l10n.collapseSidebar}):b(".collapse-sidebar").attr({"aria-expanded":"false","aria-label":f.l10n.expandSidebar})}),b("body").on("keydown",function(a){var b,c=[],d=[],e=[];27===a.which&&(f.control.each(function(a){a.expanded&&a.expanded()&&_.isFunction(a.collapse)&&c.push(a)}),f.section.each(function(a){a.expanded()&&d.push(a)}),f.panel.each(function(a){a.expanded()&&e.push(a)}),c.length>0&&0===d.length&&(c.length=0),b=c[0]||d[0]||e[0],b&&(b.collapse(),a.preventDefault()))}),b(".customize-controls-preview-toggle").on("click",function(){d.toggleClass("preview-only")}),f.previewedDevice=new f.Value,f.bind("ready",function(){_.find(f.settings.previewableDevices,function(a,b){return!0===a["default"]?(f.previewedDevice.set(b),!0):void 0})}),i.find(".devices button").on("click",function(a){f.previewedDevice.set(b(a.currentTarget).data("device"))}),f.previewedDevice.bind(function(a){var c=b(".wp-full-overlay"),d="";i.find(".devices button").removeClass("active").attr("aria-pressed",!1),i.find(".devices .preview-"+a).addClass("active").attr("aria-pressed",!0),b.each(f.settings.previewableDevices,function(a){d+=" preview-"+a}),c.removeClass(d).addClass("preview-"+a)}),e.length&&f("blogname",function(a){var c=function(){e.text(b.trim(a())||f.l10n.untitledBlogName)};a.bind(c),c()}),a=new f.Messenger({url:f.settings.url.parent,channel:"loader"}),a.bind("back",function(){g.on("click.customize-controls-close",function(b){b.preventDefault(),a.send("close")})}),b(window).on("beforeunload.customize-confirm",function(){return f.state("saved")()?void 0:(setTimeout(function(){d.removeClass("customize-loading")},1),f.l10n.saveAlert)}),b.each(["saved","change"],function(b,c){f.bind(c,function(){a.send(c)})}),f.bind("title",function(b){a.send("title",b)}),a.send("changeset-uuid",f.settings.changeset.uuid),a.send("ready"),b.each({background_image:{controls:["background_repeat","background_position_x","background_attachment"],callback:function(a){return!!a}},show_on_front:{controls:["page_on_front","page_for_posts"],callback:function(a){return"page"===a}},header_textcolor:{controls:["header_textcolor"],callback:function(a){return"blank"!==a}}},function(a,c){f(a,function(a){b.each(c.controls,function(b,d){f.control(d,function(b){var d=function(a){b.container.toggle(c.callback(a))};d(a.get()),a.bind(d)})})})}),f.control("display_header_text",function(a){var b="";a.elements[0].unsync(f("header_textcolor")),a.element=new f.Element(a.container.find("input")),a.element.set("blank"!==a.setting()),a.element.bind(function(c){c||(b=f("header_textcolor").get()),a.setting.set(c?b:"blank")}),a.setting.bind(function(b){a.element.set("blank"!==b)})}),f("show_on_front","page_on_front",function(a,b){var c=function(){"page"===a()&&parseInt(b(),10)>0&&f.previewer.previewUrl.set(f.settings.url.home)};a.bind(c),b.bind(c)}),f("page_for_posts",function(a){a.bind(function(a){a=parseInt(a,10),a>0&&f.previewer.previewUrl.set(f.settings.url.home+"?page_id="+a)})}),f.previewer.bind("selective-refresh-setting-validities",function(a){f._handleSettingValidities({settingValidities:a,focusInvalidControl:!1})}),f.previewer.bind("focus-control-for-setting",function(a){var b;f.control.each(function(c){var d=_.pluck(c.settings,"id");-1!==_.indexOf(d,a)&&(b=c)}),b&&b.focus()}),f.previewer.bind("refresh",function(){f.previewer.refresh()}),function(){var a,c,d,e=!1;c=function(){e||(e=!0,f.requestChangesetUpdate().always(function(){e=!1})),d()},d=function(){clearTimeout(a),a=setTimeout(function(){c()},f.settings.timeouts.changesetAutoSave)},d(),b(window).on("blur.wp-customize-changeset-update",function(){c()}),b(window).on("beforeunload.wp-customize-changeset-update",function(){c()})}(),f.trigger("ready")}})}(wp,jQuery);
\ No newline at end of file
diff --git a/wp-admin/js/customize-widgets.js b/wp-admin/js/customize-widgets.js
index 2799b82616..25c1eb5b7a 100644
--- a/wp-admin/js/customize-widgets.js
+++ b/wp-admin/js/customize-widgets.js
@@ -1154,7 +1154,7 @@
 			params.action = 'update-widget';
 			params.wp_customize = 'on';
 			params.nonce = api.settings.nonce['update-widget'];
-			params.theme = api.settings.theme.stylesheet;
+			params.customize_theme = api.settings.theme.stylesheet;
 			params.customized = wp.customize.previewer.query().customized;
 
 			data = $.param( params );
diff --git a/wp-admin/js/customize-widgets.min.js b/wp-admin/js/customize-widgets.min.js
index 0e47f60078..feff840dd9 100644
--- a/wp-admin/js/customize-widgets.min.js
+++ b/wp-admin/js/customize-widgets.min.js
@@ -1 +1 @@
-!function(a,b){function c(a,b){function c(d){d||(a.expanded.unbind(c),b.focus())}a.focus(),a.expanded.bind(c)}function d(a){var b,c={number:null,id_base:null};return b=a.match(/^(.+)-(\d+)$/),b?(c.id_base=b[1],c.number=parseInt(b[2],10)):c.id_base=a,c}function e(a){var b,c=d(a);return b="widget_"+c.id_base,c.number&&(b+="["+c.number+"]"),b}if(a&&a.customize){var f,g=a.customize;g.Widgets=g.Widgets||{},g.Widgets.savedWidgetIds={},g.Widgets.data=_wpCustomizeWidgetsSettings||{},f=g.Widgets.data.l10n,delete g.Widgets.data.l10n,g.Widgets.WidgetModel=Backbone.Model.extend({id:null,temp_id:null,classname:null,control_tpl:null,description:null,is_disabled:null,is_multi:null,multi_number:null,name:null,id_base:null,transport:null,params:[],width:null,height:null,search_matched:!0}),g.Widgets.WidgetCollection=Backbone.Collection.extend({model:g.Widgets.WidgetModel,doSearch:function(a){this.terms!==a&&(this.terms=a,this.terms.length>0&&this.search(this.terms),""===this.terms&&this.each(function(a){a.set("search_matched",!0)}))},search:function(a){var b,c;a=a.replace(/[-\/\\^$*+?.()|[\]{}]/g,"\\$&"),a=a.replace(/ /g,")(?=.*"),b=new RegExp("^(?=.*"+a+").+","i"),this.each(function(a){c=[a.get("name"),a.get("id"),a.get("description")].join(" "),a.set("search_matched",b.test(c))})}}),g.Widgets.availableWidgets=new g.Widgets.WidgetCollection(g.Widgets.data.availableWidgets),g.Widgets.SidebarModel=Backbone.Model.extend({after_title:null,after_widget:null,before_title:null,before_widget:null,"class":null,description:null,id:null,name:null,is_rendered:!1}),g.Widgets.SidebarCollection=Backbone.Collection.extend({model:g.Widgets.SidebarModel}),g.Widgets.registeredSidebars=new g.Widgets.SidebarCollection(g.Widgets.data.registeredSidebars),g.Widgets.AvailableWidgetsPanelView=a.Backbone.View.extend({el:"#available-widgets",events:{"input #widgets-search":"search","keyup #widgets-search":"search","focus .widget-tpl":"focus","click .widget-tpl":"_submit","keypress .widget-tpl":"_submit",keydown:"keyboardAccessible"},selected:null,currentSidebarControl:null,$search:null,$clearResults:null,searchMatchesCount:null,initialize:function(){var a=this;this.$search=b("#widgets-search"),this.$clearResults=this.$el.find(".clear-results"),_.bindAll(this,"close"),this.listenTo(this.collection,"change",this.updateList),this.updateList(),this.searchMatchesCount=this.collection.length,b("#customize-controls, #available-widgets .customize-section-title").on("click keydown",function(c){var d=b(c.target).is(".add-new-widget, .add-new-widget *");b("body").hasClass("adding-widget")&&!d&&a.close()}),this.$clearResults.on("click",function(){a.$search.val("").focus().trigger("keyup")}),g.previewer.bind("url",this.close)},search:function(a){var b;this.collection.doSearch(a.target.value),this.updateSearchMatchesCount(),this.announceSearchMatches(),this.selected&&!this.selected.is(":visible")&&(this.selected.removeClass("selected"),this.selected=null),this.selected&&!a.target.value&&(this.selected.removeClass("selected"),this.selected=null),!this.selected&&a.target.value&&(b=this.$el.find("> .widget-tpl:visible:first"),b.length&&this.select(b)),""!==a.target.value?this.$clearResults.addClass("is-visible"):""===a.target.value&&this.$clearResults.removeClass("is-visible"),this.searchMatchesCount?this.$el.removeClass("no-widgets-found"):this.$el.addClass("no-widgets-found")},updateSearchMatchesCount:function(){this.searchMatchesCount=this.collection.where({search_matched:!0}).length},announceSearchMatches:_.debounce(function(){var b=f.widgetsFound.replace("%d",this.searchMatchesCount);this.searchMatchesCount||(b=f.noWidgetsFound),a.a11y.speak(b)},500),updateList:function(){this.collection.each(function(a){var c=b("#widget-tpl-"+a.id);c.toggle(a.get("search_matched")&&!a.get("is_disabled")),a.get("is_disabled")&&c.is(this.selected)&&(this.selected=null)})},select:function(a){this.selected=b(a),this.selected.siblings(".widget-tpl").removeClass("selected"),this.selected.addClass("selected")},focus:function(a){this.select(b(a.currentTarget))},_submit:function(a){"keypress"===a.type&&13!==a.which&&32!==a.which||this.submit(b(a.currentTarget))},submit:function(a){var c,d,e;a||(a=this.selected),a&&this.currentSidebarControl&&(this.select(a),c=b(this.selected).data("widget-id"),d=this.collection.findWhere({id:c}),d&&(e=this.currentSidebarControl.addWidget(d.get("id_base")),e&&e.focus(),this.close()))},open:function(a){this.currentSidebarControl=a,_(this.currentSidebarControl.getWidgetFormControls()).each(function(a){a.params.is_wide&&a.collapseForm()}),b("body").addClass("adding-widget"),this.$el.find(".selected").removeClass("selected"),this.collection.doSearch(""),g.settings.browser.mobile||this.$search.focus()},close:function(a){a=a||{},a.returnFocus&&this.currentSidebarControl&&this.currentSidebarControl.container.find(".add-new-widget").focus(),this.currentSidebarControl=null,this.selected=null,b("body").removeClass("adding-widget"),this.$search.val("")},keyboardAccessible:function(a){var c=13===a.which,d=27===a.which,e=40===a.which,f=38===a.which,g=9===a.which,h=a.shiftKey,i=null,j=this.$el.find("> .widget-tpl:visible:first"),k=this.$el.find("> .widget-tpl:visible:last"),l=b(a.target).is(this.$search),m=b(a.target).is(".widget-tpl:visible:last");return e||f?(e?l?i=j:this.selected&&0!==this.selected.nextAll(".widget-tpl:visible").length&&(i=this.selected.nextAll(".widget-tpl:visible:first")):f&&(l?i=k:this.selected&&0!==this.selected.prevAll(".widget-tpl:visible").length&&(i=this.selected.prevAll(".widget-tpl:visible:first"))),this.select(i),void(i?i.focus():this.$search.focus())):void(c&&!this.$search.val()||(c?this.submit():d&&this.close({returnFocus:!0}),this.currentSidebarControl&&g&&(h&&l||!h&&m)&&(this.currentSidebarControl.container.find(".add-new-widget").focus(),a.preventDefault())))}}),g.Widgets.formSyncHandlers={rss:function(a,c,d){var e=c.find(".widget-error:first"),f=b("<div>"+d+"</div>").find(".widget-error:first");e.length&&f.length?e.replaceWith(f):e.length?e.remove():f.length&&c.find(".widget-content:first").prepend(f)}},g.Widgets.WidgetControl=g.Control.extend({defaultExpandedArguments:{duration:"fast",completeCallback:b.noop},initialize:function(a,c){var d=this;d.widgetControlEmbedded=!1,d.widgetContentEmbedded=!1,d.expanded=new g.Value(!1),d.expandedArgumentsQueue=[],d.expanded.bind(function(a){var c=d.expandedArgumentsQueue.shift();c=b.extend({},d.defaultExpandedArguments,c),d.onChangeExpanded(a,c)}),d.altNotice=!0,g.Control.prototype.initialize.call(d,a,c)},ready:function(){var a=this;a.section()?g.section(a.section(),function(b){var c=function(d){d&&(a.embedWidgetControl(),b.expanded.unbind(c))};b.expanded()?c(!0):b.expanded.bind(c)}):a.embedWidgetControl()},embedWidgetControl:function(){var a,c=this;c.widgetControlEmbedded||(c.widgetControlEmbedded=!0,a=b(c.params.widget_control),c.container.append(a),c._setupModel(),c._setupWideWidget(),c._setupControlToggle(),c._setupWidgetTitle(),c._setupReorderUI(),c._setupHighlightEffects(),c._setupUpdateUI(),c._setupRemoveUI())},embedWidgetContent:function(){var a,c=this;c.embedWidgetControl(),c.widgetContentEmbedded||(c.widgetContentEmbedded=!0,a=b(c.params.widget_content),c.container.find(".widget-content:first").append(a),b(document).trigger("widget-added",[c.container.find(".widget:first")]))},_setupModel:function(){var a,b=this;a=function(){g.Widgets.savedWidgetIds[b.params.widget_id]=!0},g.bind("ready",a),g.bind("saved",a),this._updateCount=0,this.isWidgetUpdating=!1,this.liveUpdateMode=!0,this.setting.bind(function(a,c){_(c).isEqual(a)||b.isWidgetUpdating||b.updateWidget({instance:a})})},_setupWideWidget:function(){var a,c,d,e,f,h=this;this.params.is_wide&&(a=this.container.find(".widget-inside"),c=a.find("> .form"),d=b(".wp-full-overlay-sidebar-content:first"),this.container.addClass("wide-widget-control"),this.container.find(".widget-content:first").css({"max-width":this.params.width,"min-height":this.params.height}),f=function(){var d,e=h.container.offset().top,f=b(window).height(),g=c.outerHeight();a.css("max-height",f),d=Math.max(0,Math.min(Math.max(e,0),f-g)),a.css("top",d)},e=b("#customize-theme-controls"),this.container.on("expand",function(){f(),d.on("scroll",f),b(window).on("resize",f),e.on("expanded collapsed",f)}),this.container.on("collapsed",function(){d.off("scroll",f),b(window).off("resize",f),e.off("expanded collapsed",f)}),g.each(function(a){0===a.id.indexOf("sidebars_widgets[")&&a.bind(function(){h.container.hasClass("expanded")&&f()})}))},_setupControlToggle:function(){var a,b=this;this.container.find(".widget-top").on("click",function(a){a.preventDefault();var c=b.getSidebarWidgetsControl();c.isReordering||b.expanded(!b.expanded())}),a=this.container.find(".widget-control-close"),a.on("click",function(a){a.preventDefault(),b.collapse(),b.container.find(".widget-top .widget-action:first").focus()})},_setupWidgetTitle:function(){var a,b=this;a=function(){var a=b.setting().title,c=b.container.find(".in-widget-title");a?c.text(": "+a):c.text("")},this.setting.bind(a),a()},_setupReorderUI:function(){var c,d,e,h,i,j=this;c=function(a){a.siblings(".selected").removeClass("selected"),a.addClass("selected");var b=a.data("id")===j.params.sidebar_id;j.container.find(".move-widget-btn").prop("disabled",b)},this.container.find(".widget-title-action").after(b(g.Widgets.data.tpl.widgetReorderNav)),i=_.template(g.Widgets.data.tpl.moveWidgetArea),d=b(i({sidebars:_(g.Widgets.registeredSidebars.toArray()).pluck("attributes")})),this.container.find(".widget-top").after(d),h=function(){var a,e=d.find("li"),f=0;a=e.filter(function(){return b(this).data("id")===j.params.sidebar_id}),e.each(function(){var d,e,h,i=b(this);d=i.data("id"),e=g.Widgets.registeredSidebars.get(d),h=e.get("is_rendered"),i.toggle(h),h&&(f+=1),i.hasClass("selected")&&!h&&c(a)}),f>1?j.container.find(".move-widget").show():j.container.find(".move-widget").hide()},h(),g.Widgets.registeredSidebars.on("change:is_rendered",h),e=this.container.find(".widget-reorder-nav"),e.find(".move-widget, .move-widget-down, .move-widget-up").each(function(){b(this).prepend(j.container.find(".widget-title").text()+": ")}).on("click keypress",function(c){if("keypress"!==c.type||13===c.which||32===c.which)if(b(this).focus(),b(this).is(".move-widget"))j.toggleWidgetMoveArea();else{var d=b(this).is(".move-widget-down"),e=b(this).is(".move-widget-up"),g=j.getWidgetSidebarPosition();if(e&&0===g||d&&g===j.getSidebarWidgetsControl().setting().length-1)return;e?(j.moveUp(),a.a11y.speak(f.widgetMovedUp)):(j.moveDown(),a.a11y.speak(f.widgetMovedDown)),b(this).focus()}}),this.container.find(".widget-area-select").on("click keypress","li",function(a){"keypress"===a.type&&13!==a.which&&32!==a.which||(a.preventDefault(),c(b(this)))}),this.container.find(".move-widget-btn").click(function(){j.getSidebarWidgetsControl().toggleReordering(!1);var a,b,c,d,e,f=j.params.sidebar_id,h=j.container.find(".widget-area-select li.selected").data("id");a=g("sidebars_widgets["+f+"]"),b=g("sidebars_widgets["+h+"]"),c=Array.prototype.slice.call(a()),d=Array.prototype.slice.call(b()),e=j.getWidgetSidebarPosition(),c.splice(e,1),d.push(j.params.widget_id),a(c),b(d),j.focus()})},_setupHighlightEffects:function(){var a=this;this.container.on("mouseenter 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b;b=c.container.next().is(".customize-control-widget_form")?c.container.next().find(".widget-action:first"):c.container.prev().is(".customize-control-widget_form")?c.container.prev().find(".widget-action:first"):c.container.next(".customize-control-sidebar_widgets").find(".add-new-widget:first"),c.container.slideUp(function(){var a,d,e=g.Widgets.getSidebarWidgetControlContainingWidget(c.params.widget_id);e&&(a=e.setting().slice(),d=_.indexOf(a,c.params.widget_id),-1!==d&&(a.splice(d,1),e.setting(a),b.focus()))})}),b=function(){a.text(f.removeBtnLabel),a.attr("title",f.removeBtnTooltip)},this.params.is_new?g.bind("saved",b):b()},_getInputs:function(a){return b(a).find(":input[name]")},_getInputsSignature:function(a){var c=_(a).map(function(a){var c,d=b(a);return c=d.is(":checkbox, :radio")?[d.attr("id"),d.attr("name"),d.prop("value")]:[d.attr("id"),d.attr("name")],c.join(",")});return c.join(";")},_getInputState:function(a){return a=b(a),a.is(":radio, :checkbox")?a.prop("checked"):a.is("select[multiple]")?a.find("option:selected").map(function(){return b(this).val()}).get():a.val()},_setInputState:function(a,c){a=b(a),a.is(":radio, :checkbox")?a.prop("checked",c):a.is("select[multiple]")?(c=b.isArray(c)?_.map(c,function(a){return String(a)}):[],a.find("option").each(function(){b(this).prop("selected",-1!==_.indexOf(c,String(this.value)))})):a.val(c)},getSidebarWidgetsControl:function(){var a,b;return a="sidebars_widgets["+this.params.sidebar_id+"]",(b=g.control(a))?b:void 0},updateWidget:function(c){var d,e,h,i,j,k,l,m,n,o,p,q=this;q.embedWidgetContent(),c=b.extend({instance:null,complete:null,ignoreActiveElement:!1},c),d=c.instance,e=c.complete,this._updateCount+=1,j=this._updateCount,h=this.container.find(".widget:first"),i=h.find(".widget-content:first"),i.find(".widget-error").remove(),this.container.addClass("widget-form-loading"),this.container.addClass("previewer-loading"),n=g.state("processing"),n(n()+1),this.liveUpdateMode||this.container.addClass("widget-form-disabled"),k={},k.action="update-widget",k.wp_customize="on",k.nonce=g.settings.nonce["update-widget"],k.theme=g.settings.theme.stylesheet,k.customized=a.customize.previewer.query().customized,l=b.param(k),m=this._getInputs(i),m.each(function(){b(this).data("state"+j,q._getInputState(this))}),l+=d?"&"+b.param({sanitized_widget_setting:JSON.stringify(d)}):"&"+m.serialize(),l+="&"+i.find("~ 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d,e,f,g=b(this),h=b(l[a]);d=g.data("state"+j),e=q._getInputState(h),g.data("sanitized",e),f=!_.isEqual(d,e)&&(c.ignoreActiveElement||!g.is(document.activeElement)),f&&q._setInputState(g,e)}),b(document).trigger("widget-synced",[h,a.data.form])):q.liveUpdateMode?(q.liveUpdateMode=!1,q.container.find('input[name="savewidget"]').show(),o=!0):(i.html(a.data.form),q.container.removeClass("widget-form-disabled"),b(document).trigger("widget-updated",[h])),p=!o&&!_(q.setting()).isEqual(a.data.instance),p?(q.isWidgetUpdating=!0,q.setting(a.data.instance),q.isWidgetUpdating=!1):q.container.removeClass("previewer-loading"),e&&e.call(q,null,{noChange:!p,ajaxFinished:!0})):(d=f.error,a.data&&a.data.message&&(d=a.data.message),e?e.call(q,d):i.prepend('<p 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i.embedWidgetControl(),a&&i.embedWidgetContent(),b.unchanged?void(a&&g.Control.prototype.expand.call(i,{completeCallback:b.completeCallback})):(c=this.container.find("div.widget:first"),d=c.find(".widget-inside:first"),h=function(){g.control.each(function(a){i.params.type===a.params.type&&i!==a&&a.collapse()}),e=function(){i.container.removeClass("expanding"),i.container.addClass("expanded"),i.container.trigger("expanded")},b.completeCallback&&(f=e,e=function(){f(),b.completeCallback()}),i.params.is_wide?d.fadeIn(b.duration,e):d.slideDown(b.duration,e),i.container.trigger("expand"),i.container.addClass("expanding")},void(a?g.section.has(i.section())?g.section(i.section()).expand({completeCallback:h}):h():(e=function(){i.container.removeClass("collapsing"),i.container.removeClass("expanded"),i.container.trigger("collapsed")},b.completeCallback&&(f=e,e=function(){f(),b.completeCallback()}),i.container.trigger("collapse"),i.container.addClass("collapsing"),i.params.is_wide?d.fadeOut(b.duration,e):d.slideUp(b.duration,function(){c.css({width:"",margin:""}),e()}))))},getWidgetSidebarPosition:function(){var a,b;return a=this.getSidebarWidgetsControl().setting(),b=_.indexOf(a,this.params.widget_id),-1!==b?b:void 0},moveUp:function(){this._moveWidgetByOne(-1)},moveDown:function(){this._moveWidgetByOne(1)},_moveWidgetByOne:function(a){var b,c,d,e;b=this.getWidgetSidebarPosition(),c=this.getSidebarWidgetsControl().setting,d=Array.prototype.slice.call(c()),e=d[b+a],d[b+a]=this.params.widget_id,d[b]=e,c(d)},toggleWidgetMoveArea:function(a){var c,d=this;c=this.container.find(".move-widget-area"),"undefined"==typeof a&&(a=!c.hasClass("active")),a&&(c.find(".selected").removeClass("selected"),c.find("li").filter(function(){return b(this).data("id")===d.params.sidebar_id}).addClass("selected"),this.container.find(".move-widget-btn").prop("disabled",!0)),c.toggleClass("active",a)},highlightSectionAndControl:function(){var a;a=this.container.is(":hidden")?this.container.closest(".control-section"):this.container,b(".highlighted").removeClass("highlighted"),a.addClass("highlighted"),setTimeout(function(){a.removeClass("highlighted")},500)}}),g.Widgets.WidgetsPanel=g.Panel.extend({ready:function(){var a=this;g.Panel.prototype.ready.call(a),a.deferred.embedded.done(function(){var c,d,e;c=a.container.find(".panel-meta"),d=b("<div></div>",{"class":"no-widget-areas-rendered-notice"}),d.append(b("<em></em>",{text:f.noAreasRendered})),c.append(d),e=function(){return 0===_.filter(a.sections(),function(a){return a.active()}).length},d.toggle(e()),g.previewer.deferred.active.done(function(){d.toggle(e())}),g.bind("pane-contents-reflowed",function(){var a="resolved"===g.previewer.deferred.active.state()?"fast":0;e()?d.slideDown(a):d.slideUp(a)})})},isContextuallyActive:function(){var a=this;return a.active()}}),g.Widgets.SidebarSection=g.Section.extend({ready:function(){var a,b=this;g.Section.prototype.ready.call(this),a=g.Widgets.registeredSidebars.get(b.params.sidebarId),b.active.bind(function(b){a.set("is_rendered",b)}),a.set("is_rendered",b.active())}}),g.Widgets.SidebarControl=g.Control.extend({ready:function(){this.$controlSection=this.container.closest(".control-section"),this.$sectionContent=this.container.closest(".accordion-section-content"),this._setupModel(),this._setupSortable(),this._setupAddition(),this._applyCardinalOrderClassNames()},_setupModel:function(){var a=this;this.setting.bind(function(c,e){var f,h,i;h=_(e).difference(c),c=_(c).filter(function(a){var b=d(a);return!!g.Widgets.availableWidgets.findWhere({id_base:b.id_base})}),f=_(c).map(function(b){var c=g.Widgets.getWidgetFormControlForWidget(b);return c||(c=a.addWidget(b)),c}),f.sort(function(a,b){var d=_.indexOf(c,a.params.widget_id),e=_.indexOf(c,b.params.widget_id);return d-e}),i=0,_(f).each(function(b){b.priority(i),b.section(a.section()),i+=1}),a.priority(i),a._applyCardinalOrderClassNames(),_(f).each(function(b){b.params.sidebar_id=a.params.sidebar_id}),_(h).each(function(c){setTimeout(function(){var e,f,h,i,j,k=!1;g.each(function(b){if(b.id!==a.setting.id&&0===b.id.indexOf("sidebars_widgets[")&&"sidebars_widgets[wp_inactive_widgets]"!==b.id){var d,e=b();d=_.indexOf(e,c),-1!==d&&(k=!0)}}),k||(e=g.Widgets.getWidgetFormControlForWidget(c),f=e&&b.contains(document,e.container[0])&&!b.contains(a.$sectionContent[0],e.container[0]),e&&!f&&(g.control.remove(e.id),e.container.remove()),g.Widgets.savedWidgetIds[c]&&(h=g.value("sidebars_widgets[wp_inactive_widgets]")().slice(),h.push(c),g.value("sidebars_widgets[wp_inactive_widgets]")(_(h).unique())),i=d(c).id_base,j=g.Widgets.availableWidgets.findWhere({id_base:i}),j&&!j.get("is_multi")&&j.set("is_disabled",!1))})})})},_setupSortable:function(){var a=this;this.isReordering=!1,this.$sectionContent.sortable({items:"> .customize-control-widget_form",handle:".widget-top",axis:"y",tolerance:"pointer",connectWith:".accordion-section-content:has(.customize-control-sidebar_widgets)",update:function(){var c,d=a.$sectionContent.sortable("toArray");c=b.map(d,function(a){return b("#"+a).find(":input[name=widget-id]").val()}),a.setting(c)}}),this.$controlSection.find(".accordion-section-title").droppable({accept:".customize-control-widget_form",over:function(){var b=g.section(a.section.get());b.expand({allowMultiple:!0,completeCallback:function(){g.section.each(function(a){a.container.find(".customize-control-sidebar_widgets").length&&a.container.find(".accordion-section-content:first").sortable("refreshPositions")})}})}}),this.container.find(".reorder-toggle").on("click",function(){a.toggleReordering(!a.isReordering)})},_setupAddition:function(){var a=this;this.container.find(".add-new-widget").on("click",function(){var c=b(this);a.$sectionContent.hasClass("reordering")||(b("body").hasClass("adding-widget")?(c.attr("aria-expanded","false"),g.Widgets.availableWidgetsPanel.close()):(c.attr("aria-expanded","true"),g.Widgets.availableWidgetsPanel.open(a)))})},_applyCardinalOrderClassNames:function(){var a=[];return _.each(this.setting(),function(b){var c=g.Widgets.getWidgetFormControlForWidget(b);c&&a.push(c)}),0===a.length||1===g.Widgets.registeredSidebars.length&&a.length<=1?void this.container.find(".reorder-toggle").hide():(this.container.find(".reorder-toggle").show(),b(a).each(function(){b(this.container).removeClass("first-widget").removeClass("last-widget").find(".move-widget-down, .move-widget-up").prop("tabIndex",0)}),_.first(a).container.addClass("first-widget").find(".move-widget-up").prop("tabIndex",-1),void _.last(a).container.addClass("last-widget").find(".move-widget-down").prop("tabIndex",-1))},toggleReordering:function(b){var c=this.$sectionContent.find(".add-new-widget"),d=this.container.find(".reorder-toggle"),e=this.$sectionContent.find(".widget-title");b=Boolean(b),b!==this.$sectionContent.hasClass("reordering")&&(this.isReordering=b,this.$sectionContent.toggleClass("reordering",b),b?(_(this.getWidgetFormControls()).each(function(a){a.collapse()}),c.attr({tabindex:"-1","aria-hidden":"true"}),d.attr("aria-label",f.reorderLabelOff),a.a11y.speak(f.reorderModeOn),e.attr("aria-hidden","true")):(c.removeAttr("tabindex aria-hidden"),d.attr("aria-label",f.reorderLabelOn),a.a11y.speak(f.reorderModeOff),e.attr("aria-hidden","false")))},getWidgetFormControls:function(){var a=[];return _(this.setting()).each(function(b){var c=e(b),d=g.control(c);d&&a.push(d)}),a},addWidget:function(a){var c,e,f,h,i,j,k,l,m,n,o=this,p="widget_form",q=d(a),r=q.number,s=q.id_base,t=g.Widgets.availableWidgets.findWhere({id_base:s});return t?r&&!t.get("is_multi")?!1:(t.get("is_multi")&&!r&&(t.set("multi_number",t.get("multi_number")+1),r=t.get("multi_number")),c=b.trim(b("#widget-tpl-"+t.get("id")).html()),t.get("is_multi")?c=c.replace(/<[^<>]+>/g,function(a){return a.replace(/__i__|%i%/g,r)}):t.set("is_disabled",!0),e=b(c),f=b("<li/>").addClass("customize-control").addClass("customize-control-"+p).append(e),f.find("> .widget-icon").remove(),t.get("is_multi")&&(f.find('input[name="widget_number"]').val(r),f.find('input[name="multi_number"]').val(r)),a=f.find('[name="widget-id"]').val(),f.hide(),i="widget_"+t.get("id_base"),t.get("is_multi")&&(i+="["+r+"]"),f.attr("id","customize-control-"+i.replace(/\]/g,"").replace(/\[/g,"-")),j=g.has(i),j||(m={transport:g.Widgets.data.selectiveRefreshableWidgets[t.get("id_base")]?"postMessage":"refresh",previewer:this.setting.previewer},n=g.create(i,i,"",m),n.set({})),h=g.controlConstructor[p],k=new h(i,{params:{settings:{"default":i},content:f,sidebar_id:o.params.sidebar_id,widget_id:a,widget_id_base:t.get("id_base"),type:p,is_new:!j,width:t.get("width"),height:t.get("height"),is_wide:t.get("is_wide"),active:!0},previewer:o.setting.previewer}),g.control.add(i,k),g.each(function(b){if(b.id!==o.setting.id&&0===b.id.indexOf("sidebars_widgets[")){var c=b().slice(),d=_.indexOf(c,a);-1!==d&&(c.splice(d),b(c))}}),l=this.setting().slice(),-1===_.indexOf(l,a)&&(l.push(a),this.setting(l)),f.slideDown(function(){j&&k.updateWidget({instance:k.setting()})}),k):!1}}),b.extend(g.panelConstructor,{widgets:g.Widgets.WidgetsPanel}),b.extend(g.sectionConstructor,{sidebar:g.Widgets.SidebarSection}),b.extend(g.controlConstructor,{widget_form:g.Widgets.WidgetControl,sidebar_widgets:g.Widgets.SidebarControl}),g.bind("ready",function(){g.Widgets.availableWidgetsPanel=new g.Widgets.AvailableWidgetsPanelView({collection:g.Widgets.availableWidgets}),g.previewer.bind("highlight-widget-control",g.Widgets.highlightWidgetFormControl),g.previewer.bind("focus-widget-control",g.Widgets.focusWidgetFormControl)}),g.Widgets.highlightWidgetFormControl=function(a){var b=g.Widgets.getWidgetFormControlForWidget(a);b&&b.highlightSectionAndControl()},g.Widgets.focusWidgetFormControl=function(a){var b=g.Widgets.getWidgetFormControlForWidget(a);b&&b.focus()},g.Widgets.getSidebarWidgetControlContainingWidget=function(a){var b=null;return g.control.each(function(c){"sidebar_widgets"===c.params.type&&-1!==_.indexOf(c.setting(),a)&&(b=c)}),b},g.Widgets.getWidgetFormControlForWidget=function(a){var b=null;return g.control.each(function(c){"widget_form"===c.params.type&&c.params.widget_id===a&&(b=c)}),b},b(document).on("widget-added",function(a,b){var e,f,h,i;e=d(b.find("> .widget-inside > .form > 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\ No newline at end of file
+!function(a,b){function c(a,b){function c(d){d||(a.expanded.unbind(c),b.focus())}a.focus(),a.expanded.bind(c)}function d(a){var b,c={number:null,id_base:null};return b=a.match(/^(.+)-(\d+)$/),b?(c.id_base=b[1],c.number=parseInt(b[2],10)):c.id_base=a,c}function e(a){var b,c=d(a);return b="widget_"+c.id_base,c.number&&(b+="["+c.number+"]"),b}if(a&&a.customize){var f,g=a.customize;g.Widgets=g.Widgets||{},g.Widgets.savedWidgetIds={},g.Widgets.data=_wpCustomizeWidgetsSettings||{},f=g.Widgets.data.l10n,delete g.Widgets.data.l10n,g.Widgets.WidgetModel=Backbone.Model.extend({id:null,temp_id:null,classname:null,control_tpl:null,description:null,is_disabled:null,is_multi:null,multi_number:null,name:null,id_base:null,transport:null,params:[],width:null,height:null,search_matched:!0}),g.Widgets.WidgetCollection=Backbone.Collection.extend({model:g.Widgets.WidgetModel,doSearch:function(a){this.terms!==a&&(this.terms=a,this.terms.length>0&&this.search(this.terms),""===this.terms&&this.each(function(a){a.set("search_matched",!0)}))},search:function(a){var b,c;a=a.replace(/[-\/\\^$*+?.()|[\]{}]/g,"\\$&"),a=a.replace(/ /g,")(?=.*"),b=new RegExp("^(?=.*"+a+").+","i"),this.each(function(a){c=[a.get("name"),a.get("id"),a.get("description")].join(" "),a.set("search_matched",b.test(c))})}}),g.Widgets.availableWidgets=new g.Widgets.WidgetCollection(g.Widgets.data.availableWidgets),g.Widgets.SidebarModel=Backbone.Model.extend({after_title:null,after_widget:null,before_title:null,before_widget:null,"class":null,description:null,id:null,name:null,is_rendered:!1}),g.Widgets.SidebarCollection=Backbone.Collection.extend({model:g.Widgets.SidebarModel}),g.Widgets.registeredSidebars=new g.Widgets.SidebarCollection(g.Widgets.data.registeredSidebars),g.Widgets.AvailableWidgetsPanelView=a.Backbone.View.extend({el:"#available-widgets",events:{"input #widgets-search":"search","keyup #widgets-search":"search","focus .widget-tpl":"focus","click .widget-tpl":"_submit","keypress .widget-tpl":"_submit",keydown:"keyboardAccessible"},selected:null,currentSidebarControl:null,$search:null,$clearResults:null,searchMatchesCount:null,initialize:function(){var a=this;this.$search=b("#widgets-search"),this.$clearResults=this.$el.find(".clear-results"),_.bindAll(this,"close"),this.listenTo(this.collection,"change",this.updateList),this.updateList(),this.searchMatchesCount=this.collection.length,b("#customize-controls, #available-widgets .customize-section-title").on("click keydown",function(c){var d=b(c.target).is(".add-new-widget, .add-new-widget *");b("body").hasClass("adding-widget")&&!d&&a.close()}),this.$clearResults.on("click",function(){a.$search.val("").focus().trigger("keyup")}),g.previewer.bind("url",this.close)},search:function(a){var b;this.collection.doSearch(a.target.value),this.updateSearchMatchesCount(),this.announceSearchMatches(),this.selected&&!this.selected.is(":visible")&&(this.selected.removeClass("selected"),this.selected=null),this.selected&&!a.target.value&&(this.selected.removeClass("selected"),this.selected=null),!this.selected&&a.target.value&&(b=this.$el.find("> .widget-tpl:visible:first"),b.length&&this.select(b)),""!==a.target.value?this.$clearResults.addClass("is-visible"):""===a.target.value&&this.$clearResults.removeClass("is-visible"),this.searchMatchesCount?this.$el.removeClass("no-widgets-found"):this.$el.addClass("no-widgets-found")},updateSearchMatchesCount:function(){this.searchMatchesCount=this.collection.where({search_matched:!0}).length},announceSearchMatches:_.debounce(function(){var b=f.widgetsFound.replace("%d",this.searchMatchesCount);this.searchMatchesCount||(b=f.noWidgetsFound),a.a11y.speak(b)},500),updateList:function(){this.collection.each(function(a){var c=b("#widget-tpl-"+a.id);c.toggle(a.get("search_matched")&&!a.get("is_disabled")),a.get("is_disabled")&&c.is(this.selected)&&(this.selected=null)})},select:function(a){this.selected=b(a),this.selected.siblings(".widget-tpl").removeClass("selected"),this.selected.addClass("selected")},focus:function(a){this.select(b(a.currentTarget))},_submit:function(a){"keypress"===a.type&&13!==a.which&&32!==a.which||this.submit(b(a.currentTarget))},submit:function(a){var c,d,e;a||(a=this.selected),a&&this.currentSidebarControl&&(this.select(a),c=b(this.selected).data("widget-id"),d=this.collection.findWhere({id:c}),d&&(e=this.currentSidebarControl.addWidget(d.get("id_base")),e&&e.focus(),this.close()))},open:function(a){this.currentSidebarControl=a,_(this.currentSidebarControl.getWidgetFormControls()).each(function(a){a.params.is_wide&&a.collapseForm()}),b("body").addClass("adding-widget"),this.$el.find(".selected").removeClass("selected"),this.collection.doSearch(""),g.settings.browser.mobile||this.$search.focus()},close:function(a){a=a||{},a.returnFocus&&this.currentSidebarControl&&this.currentSidebarControl.container.find(".add-new-widget").focus(),this.currentSidebarControl=null,this.selected=null,b("body").removeClass("adding-widget"),this.$search.val("")},keyboardAccessible:function(a){var c=13===a.which,d=27===a.which,e=40===a.which,f=38===a.which,g=9===a.which,h=a.shiftKey,i=null,j=this.$el.find("> .widget-tpl:visible:first"),k=this.$el.find("> .widget-tpl:visible:last"),l=b(a.target).is(this.$search),m=b(a.target).is(".widget-tpl:visible:last");return e||f?(e?l?i=j:this.selected&&0!==this.selected.nextAll(".widget-tpl:visible").length&&(i=this.selected.nextAll(".widget-tpl:visible:first")):f&&(l?i=k:this.selected&&0!==this.selected.prevAll(".widget-tpl:visible").length&&(i=this.selected.prevAll(".widget-tpl:visible:first"))),this.select(i),void(i?i.focus():this.$search.focus())):void(c&&!this.$search.val()||(c?this.submit():d&&this.close({returnFocus:!0}),this.currentSidebarControl&&g&&(h&&l||!h&&m)&&(this.currentSidebarControl.container.find(".add-new-widget").focus(),a.preventDefault())))}}),g.Widgets.formSyncHandlers={rss:function(a,c,d){var e=c.find(".widget-error:first"),f=b("<div>"+d+"</div>").find(".widget-error:first");e.length&&f.length?e.replaceWith(f):e.length?e.remove():f.length&&c.find(".widget-content:first").prepend(f)}},g.Widgets.WidgetControl=g.Control.extend({defaultExpandedArguments:{duration:"fast",completeCallback:b.noop},initialize:function(a,c){var d=this;d.widgetControlEmbedded=!1,d.widgetContentEmbedded=!1,d.expanded=new g.Value(!1),d.expandedArgumentsQueue=[],d.expanded.bind(function(a){var c=d.expandedArgumentsQueue.shift();c=b.extend({},d.defaultExpandedArguments,c),d.onChangeExpanded(a,c)}),d.altNotice=!0,g.Control.prototype.initialize.call(d,a,c)},ready:function(){var a=this;a.section()?g.section(a.section(),function(b){var c=function(d){d&&(a.embedWidgetControl(),b.expanded.unbind(c))};b.expanded()?c(!0):b.expanded.bind(c)}):a.embedWidgetControl()},embedWidgetControl:function(){var a,c=this;c.widgetControlEmbedded||(c.widgetControlEmbedded=!0,a=b(c.params.widget_control),c.container.append(a),c._setupModel(),c._setupWideWidget(),c._setupControlToggle(),c._setupWidgetTitle(),c._setupReorderUI(),c._setupHighlightEffects(),c._setupUpdateUI(),c._setupRemoveUI())},embedWidgetContent:function(){var a,c=this;c.embedWidgetControl(),c.widgetContentEmbedded||(c.widgetContentEmbedded=!0,a=b(c.params.widget_content),c.container.find(".widget-content:first").append(a),b(document).trigger("widget-added",[c.container.find(".widget:first")]))},_setupModel:function(){var a,b=this;a=function(){g.Widgets.savedWidgetIds[b.params.widget_id]=!0},g.bind("ready",a),g.bind("saved",a),this._updateCount=0,this.isWidgetUpdating=!1,this.liveUpdateMode=!0,this.setting.bind(function(a,c){_(c).isEqual(a)||b.isWidgetUpdating||b.updateWidget({instance:a})})},_setupWideWidget:function(){var a,c,d,e,f,h=this;this.params.is_wide&&(a=this.container.find(".widget-inside"),c=a.find("> .form"),d=b(".wp-full-overlay-sidebar-content:first"),this.container.addClass("wide-widget-control"),this.container.find(".widget-content:first").css({"max-width":this.params.width,"min-height":this.params.height}),f=function(){var d,e=h.container.offset().top,f=b(window).height(),g=c.outerHeight();a.css("max-height",f),d=Math.max(0,Math.min(Math.max(e,0),f-g)),a.css("top",d)},e=b("#customize-theme-controls"),this.container.on("expand",function(){f(),d.on("scroll",f),b(window).on("resize",f),e.on("expanded collapsed",f)}),this.container.on("collapsed",function(){d.off("scroll",f),b(window).off("resize",f),e.off("expanded collapsed",f)}),g.each(function(a){0===a.id.indexOf("sidebars_widgets[")&&a.bind(function(){h.container.hasClass("expanded")&&f()})}))},_setupControlToggle:function(){var a,b=this;this.container.find(".widget-top").on("click",function(a){a.preventDefault();var c=b.getSidebarWidgetsControl();c.isReordering||b.expanded(!b.expanded())}),a=this.container.find(".widget-control-close"),a.on("click",function(a){a.preventDefault(),b.collapse(),b.container.find(".widget-top .widget-action:first").focus()})},_setupWidgetTitle:function(){var a,b=this;a=function(){var a=b.setting().title,c=b.container.find(".in-widget-title");a?c.text(": "+a):c.text("")},this.setting.bind(a),a()},_setupReorderUI:function(){var c,d,e,h,i,j=this;c=function(a){a.siblings(".selected").removeClass("selected"),a.addClass("selected");var b=a.data("id")===j.params.sidebar_id;j.container.find(".move-widget-btn").prop("disabled",b)},this.container.find(".widget-title-action").after(b(g.Widgets.data.tpl.widgetReorderNav)),i=_.template(g.Widgets.data.tpl.moveWidgetArea),d=b(i({sidebars:_(g.Widgets.registeredSidebars.toArray()).pluck("attributes")})),this.container.find(".widget-top").after(d),h=function(){var a,e=d.find("li"),f=0;a=e.filter(function(){return b(this).data("id")===j.params.sidebar_id}),e.each(function(){var d,e,h,i=b(this);d=i.data("id"),e=g.Widgets.registeredSidebars.get(d),h=e.get("is_rendered"),i.toggle(h),h&&(f+=1),i.hasClass("selected")&&!h&&c(a)}),f>1?j.container.find(".move-widget").show():j.container.find(".move-widget").hide()},h(),g.Widgets.registeredSidebars.on("change:is_rendered",h),e=this.container.find(".widget-reorder-nav"),e.find(".move-widget, .move-widget-down, .move-widget-up").each(function(){b(this).prepend(j.container.find(".widget-title").text()+": ")}).on("click keypress",function(c){if("keypress"!==c.type||13===c.which||32===c.which)if(b(this).focus(),b(this).is(".move-widget"))j.toggleWidgetMoveArea();else{var d=b(this).is(".move-widget-down"),e=b(this).is(".move-widget-up"),g=j.getWidgetSidebarPosition();if(e&&0===g||d&&g===j.getSidebarWidgetsControl().setting().length-1)return;e?(j.moveUp(),a.a11y.speak(f.widgetMovedUp)):(j.moveDown(),a.a11y.speak(f.widgetMovedDown)),b(this).focus()}}),this.container.find(".widget-area-select").on("click keypress","li",function(a){"keypress"===a.type&&13!==a.which&&32!==a.which||(a.preventDefault(),c(b(this)))}),this.container.find(".move-widget-btn").click(function(){j.getSidebarWidgetsControl().toggleReordering(!1);var a,b,c,d,e,f=j.params.sidebar_id,h=j.container.find(".widget-area-select li.selected").data("id");a=g("sidebars_widgets["+f+"]"),b=g("sidebars_widgets["+h+"]"),c=Array.prototype.slice.call(a()),d=Array.prototype.slice.call(b()),e=j.getWidgetSidebarPosition(),c.splice(e,1),d.push(j.params.widget_id),a(c),b(d),j.focus()})},_setupHighlightEffects:function(){var a=this;this.container.on("mouseenter click",function(){a.setting.previewer.send("highlight-widget",a.params.widget_id)}),this.setting.bind(function(){a.setting.previewer.send("highlight-widget",a.params.widget_id)})},_setupUpdateUI:function(){var a,c,d,e,h,i=this;a=this.container.find(".widget:first"),c=a.find(".widget-content:first"),d=this.container.find(".widget-control-save"),d.val(f.saveBtnLabel),d.attr("title",f.saveBtnTooltip),d.removeClass("button-primary"),d.on("click",function(a){a.preventDefault(),i.updateWidget({disable_form:!0})}),e=_.debounce(function(){i.updateWidget()},250),c.on("keydown","input",function(a){13===a.which&&(a.preventDefault(),i.updateWidget({ignoreActiveElement:!0}))}),c.on("change input propertychange",":input",function(a){i.liveUpdateMode&&("change"===a.type||this.checkValidity&&this.checkValidity())&&e()}),this.setting.previewer.channel.bind("synced",function(){i.container.removeClass("previewer-loading")}),g.previewer.bind("widget-updated",function(a){a===i.params.widget_id&&i.container.removeClass("previewer-loading")}),h=g.Widgets.formSyncHandlers[this.params.widget_id_base],h&&b(document).on("widget-synced",function(b,c){a.is(c)&&h.apply(document,arguments)})},onChangeActive:function(a,b){this.container.toggleClass("widget-rendered",a),b.completeCallback&&b.completeCallback()},_setupRemoveUI:function(){var a,b,c=this;a=this.container.find("a.widget-control-remove"),a.on("click",function(a){a.preventDefault();var b;b=c.container.next().is(".customize-control-widget_form")?c.container.next().find(".widget-action:first"):c.container.prev().is(".customize-control-widget_form")?c.container.prev().find(".widget-action:first"):c.container.next(".customize-control-sidebar_widgets").find(".add-new-widget:first"),c.container.slideUp(function(){var a,d,e=g.Widgets.getSidebarWidgetControlContainingWidget(c.params.widget_id);e&&(a=e.setting().slice(),d=_.indexOf(a,c.params.widget_id),-1!==d&&(a.splice(d,1),e.setting(a),b.focus()))})}),b=function(){a.text(f.removeBtnLabel),a.attr("title",f.removeBtnTooltip)},this.params.is_new?g.bind("saved",b):b()},_getInputs:function(a){return b(a).find(":input[name]")},_getInputsSignature:function(a){var c=_(a).map(function(a){var c,d=b(a);return c=d.is(":checkbox, :radio")?[d.attr("id"),d.attr("name"),d.prop("value")]:[d.attr("id"),d.attr("name")],c.join(",")});return c.join(";")},_getInputState:function(a){return a=b(a),a.is(":radio, :checkbox")?a.prop("checked"):a.is("select[multiple]")?a.find("option:selected").map(function(){return b(this).val()}).get():a.val()},_setInputState:function(a,c){a=b(a),a.is(":radio, :checkbox")?a.prop("checked",c):a.is("select[multiple]")?(c=b.isArray(c)?_.map(c,function(a){return String(a)}):[],a.find("option").each(function(){b(this).prop("selected",-1!==_.indexOf(c,String(this.value)))})):a.val(c)},getSidebarWidgetsControl:function(){var a,b;return a="sidebars_widgets["+this.params.sidebar_id+"]",(b=g.control(a))?b:void 0},updateWidget:function(c){var d,e,h,i,j,k,l,m,n,o,p,q=this;q.embedWidgetContent(),c=b.extend({instance:null,complete:null,ignoreActiveElement:!1},c),d=c.instance,e=c.complete,this._updateCount+=1,j=this._updateCount,h=this.container.find(".widget:first"),i=h.find(".widget-content:first"),i.find(".widget-error").remove(),this.container.addClass("widget-form-loading"),this.container.addClass("previewer-loading"),n=g.state("processing"),n(n()+1),this.liveUpdateMode||this.container.addClass("widget-form-disabled"),k={},k.action="update-widget",k.wp_customize="on",k.nonce=g.settings.nonce["update-widget"],k.customize_theme=g.settings.theme.stylesheet,k.customized=a.customize.previewer.query().customized,l=b.param(k),m=this._getInputs(i),m.each(function(){b(this).data("state"+j,q._getInputState(this))}),l+=d?"&"+b.param({sanitized_widget_setting:JSON.stringify(d)}):"&"+m.serialize(),l+="&"+i.find("~ :input").serialize(),this._previousUpdateRequest&&this._previousUpdateRequest.abort(),o=b.post(a.ajax.settings.url,l),this._previousUpdateRequest=o,o.done(function(a){var d,k,l,n,o=!1;return"0"===a?(g.previewer.preview.iframe.hide(),void g.previewer.login().done(function(){q.updateWidget(c),g.previewer.preview.iframe.show()})):"-1"===a?void g.previewer.cheatin():void(a.success?(k=b("<div>"+a.data.form+"</div>"),l=q._getInputs(k),n=q._getInputsSignature(m)===q._getInputsSignature(l),n&&!q.liveUpdateMode&&(q.liveUpdateMode=!0,q.container.removeClass("widget-form-disabled"),q.container.find('input[name="savewidget"]').hide()),n&&q.liveUpdateMode?(m.each(function(a){var d,e,f,g=b(this),h=b(l[a]);d=g.data("state"+j),e=q._getInputState(h),g.data("sanitized",e),f=!_.isEqual(d,e)&&(c.ignoreActiveElement||!g.is(document.activeElement)),f&&q._setInputState(g,e)}),b(document).trigger("widget-synced",[h,a.data.form])):q.liveUpdateMode?(q.liveUpdateMode=!1,q.container.find('input[name="savewidget"]').show(),o=!0):(i.html(a.data.form),q.container.removeClass("widget-form-disabled"),b(document).trigger("widget-updated",[h])),p=!o&&!_(q.setting()).isEqual(a.data.instance),p?(q.isWidgetUpdating=!0,q.setting(a.data.instance),q.isWidgetUpdating=!1):q.container.removeClass("previewer-loading"),e&&e.call(q,null,{noChange:!p,ajaxFinished:!0})):(d=f.error,a.data&&a.data.message&&(d=a.data.message),e?e.call(q,d):i.prepend('<p class="widget-error"><strong>'+d+"</strong></p>")))}),o.fail(function(a,b){e&&e.call(q,b)}),o.always(function(){q.container.removeClass("widget-form-loading"),m.each(function(){b(this).removeData("state"+j)}),n(n()-1)})},expandControlSection:function(){g.Control.prototype.expand.call(this)},_toggleExpanded:g.Section.prototype._toggleExpanded,expand:g.Section.prototype.expand,expandForm:function(){this.expand()},collapse:g.Section.prototype.collapse,collapseForm:function(){this.collapse()},toggleForm:function(a){"undefined"==typeof a&&(a=!this.expanded()),this.expanded(a)},onChangeExpanded:function(a,b){var c,d,e,f,h,i=this;return i.embedWidgetControl(),a&&i.embedWidgetContent(),b.unchanged?void(a&&g.Control.prototype.expand.call(i,{completeCallback:b.completeCallback})):(c=this.container.find("div.widget:first"),d=c.find(".widget-inside:first"),h=function(){g.control.each(function(a){i.params.type===a.params.type&&i!==a&&a.collapse()}),e=function(){i.container.removeClass("expanding"),i.container.addClass("expanded"),i.container.trigger("expanded")},b.completeCallback&&(f=e,e=function(){f(),b.completeCallback()}),i.params.is_wide?d.fadeIn(b.duration,e):d.slideDown(b.duration,e),i.container.trigger("expand"),i.container.addClass("expanding")},void(a?g.section.has(i.section())?g.section(i.section()).expand({completeCallback:h}):h():(e=function(){i.container.removeClass("collapsing"),i.container.removeClass("expanded"),i.container.trigger("collapsed")},b.completeCallback&&(f=e,e=function(){f(),b.completeCallback()}),i.container.trigger("collapse"),i.container.addClass("collapsing"),i.params.is_wide?d.fadeOut(b.duration,e):d.slideUp(b.duration,function(){c.css({width:"",margin:""}),e()}))))},getWidgetSidebarPosition:function(){var a,b;return a=this.getSidebarWidgetsControl().setting(),b=_.indexOf(a,this.params.widget_id),-1!==b?b:void 0},moveUp:function(){this._moveWidgetByOne(-1)},moveDown:function(){this._moveWidgetByOne(1)},_moveWidgetByOne:function(a){var b,c,d,e;b=this.getWidgetSidebarPosition(),c=this.getSidebarWidgetsControl().setting,d=Array.prototype.slice.call(c()),e=d[b+a],d[b+a]=this.params.widget_id,d[b]=e,c(d)},toggleWidgetMoveArea:function(a){var c,d=this;c=this.container.find(".move-widget-area"),"undefined"==typeof a&&(a=!c.hasClass("active")),a&&(c.find(".selected").removeClass("selected"),c.find("li").filter(function(){return b(this).data("id")===d.params.sidebar_id}).addClass("selected"),this.container.find(".move-widget-btn").prop("disabled",!0)),c.toggleClass("active",a)},highlightSectionAndControl:function(){var a;a=this.container.is(":hidden")?this.container.closest(".control-section"):this.container,b(".highlighted").removeClass("highlighted"),a.addClass("highlighted"),setTimeout(function(){a.removeClass("highlighted")},500)}}),g.Widgets.WidgetsPanel=g.Panel.extend({ready:function(){var a=this;g.Panel.prototype.ready.call(a),a.deferred.embedded.done(function(){var c,d,e;c=a.container.find(".panel-meta"),d=b("<div></div>",{"class":"no-widget-areas-rendered-notice"}),d.append(b("<em></em>",{text:f.noAreasRendered})),c.append(d),e=function(){return 0===_.filter(a.sections(),function(a){return a.active()}).length},d.toggle(e()),g.previewer.deferred.active.done(function(){d.toggle(e())}),g.bind("pane-contents-reflowed",function(){var a="resolved"===g.previewer.deferred.active.state()?"fast":0;e()?d.slideDown(a):d.slideUp(a)})})},isContextuallyActive:function(){var a=this;return a.active()}}),g.Widgets.SidebarSection=g.Section.extend({ready:function(){var a,b=this;g.Section.prototype.ready.call(this),a=g.Widgets.registeredSidebars.get(b.params.sidebarId),b.active.bind(function(b){a.set("is_rendered",b)}),a.set("is_rendered",b.active())}}),g.Widgets.SidebarControl=g.Control.extend({ready:function(){this.$controlSection=this.container.closest(".control-section"),this.$sectionContent=this.container.closest(".accordion-section-content"),this._setupModel(),this._setupSortable(),this._setupAddition(),this._applyCardinalOrderClassNames()},_setupModel:function(){var a=this;this.setting.bind(function(c,e){var f,h,i;h=_(e).difference(c),c=_(c).filter(function(a){var b=d(a);return!!g.Widgets.availableWidgets.findWhere({id_base:b.id_base})}),f=_(c).map(function(b){var c=g.Widgets.getWidgetFormControlForWidget(b);return c||(c=a.addWidget(b)),c}),f.sort(function(a,b){var d=_.indexOf(c,a.params.widget_id),e=_.indexOf(c,b.params.widget_id);return d-e}),i=0,_(f).each(function(b){b.priority(i),b.section(a.section()),i+=1}),a.priority(i),a._applyCardinalOrderClassNames(),_(f).each(function(b){b.params.sidebar_id=a.params.sidebar_id}),_(h).each(function(c){setTimeout(function(){var e,f,h,i,j,k=!1;g.each(function(b){if(b.id!==a.setting.id&&0===b.id.indexOf("sidebars_widgets[")&&"sidebars_widgets[wp_inactive_widgets]"!==b.id){var d,e=b();d=_.indexOf(e,c),-1!==d&&(k=!0)}}),k||(e=g.Widgets.getWidgetFormControlForWidget(c),f=e&&b.contains(document,e.container[0])&&!b.contains(a.$sectionContent[0],e.container[0]),e&&!f&&(g.control.remove(e.id),e.container.remove()),g.Widgets.savedWidgetIds[c]&&(h=g.value("sidebars_widgets[wp_inactive_widgets]")().slice(),h.push(c),g.value("sidebars_widgets[wp_inactive_widgets]")(_(h).unique())),i=d(c).id_base,j=g.Widgets.availableWidgets.findWhere({id_base:i}),j&&!j.get("is_multi")&&j.set("is_disabled",!1))})})})},_setupSortable:function(){var a=this;this.isReordering=!1,this.$sectionContent.sortable({items:"> .customize-control-widget_form",handle:".widget-top",axis:"y",tolerance:"pointer",connectWith:".accordion-section-content:has(.customize-control-sidebar_widgets)",update:function(){var c,d=a.$sectionContent.sortable("toArray");c=b.map(d,function(a){return b("#"+a).find(":input[name=widget-id]").val()}),a.setting(c)}}),this.$controlSection.find(".accordion-section-title").droppable({accept:".customize-control-widget_form",over:function(){var b=g.section(a.section.get());b.expand({allowMultiple:!0,completeCallback:function(){g.section.each(function(a){a.container.find(".customize-control-sidebar_widgets").length&&a.container.find(".accordion-section-content:first").sortable("refreshPositions")})}})}}),this.container.find(".reorder-toggle").on("click",function(){a.toggleReordering(!a.isReordering)})},_setupAddition:function(){var a=this;this.container.find(".add-new-widget").on("click",function(){var c=b(this);a.$sectionContent.hasClass("reordering")||(b("body").hasClass("adding-widget")?(c.attr("aria-expanded","false"),g.Widgets.availableWidgetsPanel.close()):(c.attr("aria-expanded","true"),g.Widgets.availableWidgetsPanel.open(a)))})},_applyCardinalOrderClassNames:function(){var a=[];return _.each(this.setting(),function(b){var c=g.Widgets.getWidgetFormControlForWidget(b);c&&a.push(c)}),0===a.length||1===g.Widgets.registeredSidebars.length&&a.length<=1?void this.container.find(".reorder-toggle").hide():(this.container.find(".reorder-toggle").show(),b(a).each(function(){b(this.container).removeClass("first-widget").removeClass("last-widget").find(".move-widget-down, .move-widget-up").prop("tabIndex",0)}),_.first(a).container.addClass("first-widget").find(".move-widget-up").prop("tabIndex",-1),void _.last(a).container.addClass("last-widget").find(".move-widget-down").prop("tabIndex",-1))},toggleReordering:function(b){var c=this.$sectionContent.find(".add-new-widget"),d=this.container.find(".reorder-toggle"),e=this.$sectionContent.find(".widget-title");b=Boolean(b),b!==this.$sectionContent.hasClass("reordering")&&(this.isReordering=b,this.$sectionContent.toggleClass("reordering",b),b?(_(this.getWidgetFormControls()).each(function(a){a.collapse()}),c.attr({tabindex:"-1","aria-hidden":"true"}),d.attr("aria-label",f.reorderLabelOff),a.a11y.speak(f.reorderModeOn),e.attr("aria-hidden","true")):(c.removeAttr("tabindex aria-hidden"),d.attr("aria-label",f.reorderLabelOn),a.a11y.speak(f.reorderModeOff),e.attr("aria-hidden","false")))},getWidgetFormControls:function(){var a=[];return _(this.setting()).each(function(b){var c=e(b),d=g.control(c);d&&a.push(d)}),a},addWidget:function(a){var c,e,f,h,i,j,k,l,m,n,o=this,p="widget_form",q=d(a),r=q.number,s=q.id_base,t=g.Widgets.availableWidgets.findWhere({id_base:s});return t?r&&!t.get("is_multi")?!1:(t.get("is_multi")&&!r&&(t.set("multi_number",t.get("multi_number")+1),r=t.get("multi_number")),c=b.trim(b("#widget-tpl-"+t.get("id")).html()),t.get("is_multi")?c=c.replace(/<[^<>]+>/g,function(a){return a.replace(/__i__|%i%/g,r)}):t.set("is_disabled",!0),e=b(c),f=b("<li/>").addClass("customize-control").addClass("customize-control-"+p).append(e),f.find("> .widget-icon").remove(),t.get("is_multi")&&(f.find('input[name="widget_number"]').val(r),f.find('input[name="multi_number"]').val(r)),a=f.find('[name="widget-id"]').val(),f.hide(),i="widget_"+t.get("id_base"),t.get("is_multi")&&(i+="["+r+"]"),f.attr("id","customize-control-"+i.replace(/\]/g,"").replace(/\[/g,"-")),j=g.has(i),j||(m={transport:g.Widgets.data.selectiveRefreshableWidgets[t.get("id_base")]?"postMessage":"refresh",previewer:this.setting.previewer},n=g.create(i,i,"",m),n.set({})),h=g.controlConstructor[p],k=new h(i,{params:{settings:{"default":i},content:f,sidebar_id:o.params.sidebar_id,widget_id:a,widget_id_base:t.get("id_base"),type:p,is_new:!j,width:t.get("width"),height:t.get("height"),is_wide:t.get("is_wide"),active:!0},previewer:o.setting.previewer}),g.control.add(i,k),g.each(function(b){if(b.id!==o.setting.id&&0===b.id.indexOf("sidebars_widgets[")){var c=b().slice(),d=_.indexOf(c,a);-1!==d&&(c.splice(d),b(c))}}),l=this.setting().slice(),-1===_.indexOf(l,a)&&(l.push(a),this.setting(l)),f.slideDown(function(){j&&k.updateWidget({instance:k.setting()})}),k):!1}}),b.extend(g.panelConstructor,{widgets:g.Widgets.WidgetsPanel}),b.extend(g.sectionConstructor,{sidebar:g.Widgets.SidebarSection}),b.extend(g.controlConstructor,{widget_form:g.Widgets.WidgetControl,sidebar_widgets:g.Widgets.SidebarControl}),g.bind("ready",function(){g.Widgets.availableWidgetsPanel=new g.Widgets.AvailableWidgetsPanelView({collection:g.Widgets.availableWidgets}),g.previewer.bind("highlight-widget-control",g.Widgets.highlightWidgetFormControl),g.previewer.bind("focus-widget-control",g.Widgets.focusWidgetFormControl)}),g.Widgets.highlightWidgetFormControl=function(a){var b=g.Widgets.getWidgetFormControlForWidget(a);b&&b.highlightSectionAndControl()},g.Widgets.focusWidgetFormControl=function(a){var b=g.Widgets.getWidgetFormControlForWidget(a);b&&b.focus()},g.Widgets.getSidebarWidgetControlContainingWidget=function(a){var b=null;return g.control.each(function(c){"sidebar_widgets"===c.params.type&&-1!==_.indexOf(c.setting(),a)&&(b=c)}),b},g.Widgets.getWidgetFormControlForWidget=function(a){var b=null;return g.control.each(function(c){"widget_form"===c.params.type&&c.params.widget_id===a&&(b=c)}),b},b(document).on("widget-added",function(a,b){var e,f,h,i;e=d(b.find("> .widget-inside > .form > .widget-id").val()),"nav_menu"===e.id_base&&(f=g.control("widget_nav_menu["+String(e.number)+"]"),f&&(h=b.find('select[name*="nav_menu"]'),i=b.find(".edit-selected-nav-menu > button"),0!==h.length&&0!==i.length&&(h.on("change",function(){g.section.has("nav_menu["+h.val()+"]")?i.parent().show():i.parent().hide()}),i.on("click",function(){var a=g.section("nav_menu["+h.val()+"]");a&&c(a,f)}))))})}}(window.wp,jQuery);
\ No newline at end of file
diff --git a/wp-includes/admin-bar.php b/wp-includes/admin-bar.php
index e87ac141f2..e95cc4d81b 100644
--- a/wp-includes/admin-bar.php
+++ b/wp-includes/admin-bar.php
@@ -366,15 +366,30 @@ function wp_admin_bar_site_menu( $wp_admin_bar ) {
  * @since 4.3.0
  *
  * @param WP_Admin_Bar $wp_admin_bar WP_Admin_Bar instance.
+ * @global WP_Customize_Manager $wp_customize
  */
 function wp_admin_bar_customize_menu( $wp_admin_bar ) {
+	global $wp_customize;
+
 	// Don't show for users who can't access the customizer or when in the admin.
 	if ( ! current_user_can( 'customize' ) || is_admin() ) {
 		return;
 	}
 
+	// Don't show if the user cannot edit a given customize_changeset post currently being previewed.
+	if ( is_customize_preview() && $wp_customize->changeset_post_id() && ! current_user_can( get_post_type_object( 'customize_changeset' )->cap->edit_post, $wp_customize->changeset_post_id() ) ) {
+		return;
+	}
+
 	$current_url = ( is_ssl() ? 'https://' : 'http://' ) . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
+	if ( is_customize_preview() && $wp_customize->changeset_uuid() ) {
+		$current_url = remove_query_arg( 'customize_changeset_uuid', $current_url );
+	}
+
 	$customize_url = add_query_arg( 'url', urlencode( $current_url ), wp_customize_url() );
+	if ( is_customize_preview() ) {
+		$customize_url = add_query_arg( array( 'changeset_uuid' => $wp_customize->changeset_uuid() ), $customize_url );
+	}
 
 	$wp_admin_bar->add_menu( array(
 		'id'     => 'customize',
diff --git a/wp-includes/class-wp-customize-manager.php b/wp-includes/class-wp-customize-manager.php
index 23e319167e..54efcd534b 100644
--- a/wp-includes/class-wp-customize-manager.php
+++ b/wp-includes/class-wp-customize-manager.php
@@ -129,15 +129,6 @@ final class WP_Customize_Manager {
 	 */
 	protected $controls = array();
 
-	/**
-	 * Return value of check_ajax_referer() in customize_preview_init() method.
-	 *
-	 * @since 3.5.0
-	 * @access protected
-	 * @var false|int
-	 */
-	protected $nonce_tick;
-
 	/**
 	 * Panel types that may be rendered from JS templates.
 	 *
@@ -192,6 +183,15 @@ final class WP_Customize_Manager {
 	 */
 	protected $autofocus = array();
 
+	/**
+	 * Messenger channel.
+	 *
+	 * @since 4.7.0
+	 * @access protected
+	 * @var string
+	 */
+	protected $messenger_channel;
+
 	/**
 	 * Unsanitized values for Customize Settings parsed from $_POST['customized'].
 	 *
@@ -199,12 +199,76 @@ final class WP_Customize_Manager {
 	 */
 	private $_post_values;
 
+	/**
+	 * Changeset UUID.
+	 *
+	 * @since 4.7.0
+	 * @access private
+	 * @var string
+	 */
+	private $_changeset_uuid;
+
+	/**
+	 * Changeset post ID.
+	 *
+	 * @since 4.7.0
+	 * @access private
+	 * @var int|false
+	 */
+	private $_changeset_post_id;
+
+	/**
+	 * Changeset data loaded from a customize_changeset post.
+	 *
+	 * @since 4.7.0
+	 * @access private
+	 * @var array
+	 */
+	private $_changeset_data;
+
 	/**
 	 * Constructor.
 	 *
 	 * @since 3.4.0
+	 * @since 4.7.0 Added $args param.
+	 *
+	 * @param array $args {
+	 *     Args.
+	 *
+	 *     @type string $changeset_uuid    Changeset UUID, the post_name for the customize_changeset post containing the customized state. Defaults to new UUID.
+	 *     @type string $theme             Theme to be previewed (for theme switch). Defaults to customize_theme or theme query params.
+	 *     @type string $messenger_channel Messenger channel. Defaults to customize_messenger_channel query param.
+	 * }
 	 */
-	public function __construct() {
+	public function __construct( $args = array() ) {
+
+		$args = array_merge(
+			array_fill_keys( array( 'changeset_uuid', 'theme', 'messenger_channel' ), null ),
+			$args
+		);
+
+		// Note that the UUID format will be validated in the setup_theme() method.
+		if ( ! isset( $args['changeset_uuid'] ) ) {
+			$args['changeset_uuid'] = wp_generate_uuid4();
+		}
+
+		// The theme and messenger_channel should be supplied via $args, but they are also looked at in the $_REQUEST global here for back-compat.
+		if ( ! isset( $args['theme'] ) ) {
+			if ( isset( $_REQUEST['customize_theme'] ) ) {
+				$args['theme'] = wp_unslash( $_REQUEST['customize_theme'] );
+			} elseif ( isset( $_REQUEST['theme'] ) ) { // Deprecated.
+				$args['theme'] = wp_unslash( $_REQUEST['theme'] );
+			}
+		}
+		if ( ! isset( $args['messenger_channel'] ) && isset( $_REQUEST['customize_messenger_channel'] ) ) {
+			$args['messenger_channel'] = sanitize_key( wp_unslash( $_REQUEST['customize_messenger_channel'] ) );
+		}
+
+		$this->original_stylesheet = get_stylesheet();
+		$this->theme = wp_get_theme( $args['theme'] );
+		$this->messenger_channel = $args['messenger_channel'];
+		$this->_changeset_uuid = $args['changeset_uuid'];
+
 		require_once( ABSPATH . WPINC . '/class-wp-customize-setting.php' );
 		require_once( ABSPATH . WPINC . '/class-wp-customize-panel.php' );
 		require_once( ABSPATH . WPINC . '/class-wp-customize-section.php' );
@@ -271,14 +335,9 @@ final class WP_Customize_Manager {
 			$this->nav_menus = new WP_Customize_Nav_Menus( $this );
 		}
 
-		add_filter( 'wp_die_handler', array( $this, 'wp_die_handler' ) );
-
 		add_action( 'setup_theme', array( $this, 'setup_theme' ) );
 		add_action( 'wp_loaded',   array( $this, 'wp_loaded' ) );
 
-		// Run wp_redirect_status late to make sure we override the status last.
-		add_action( 'wp_redirect_status', array( $this, 'wp_redirect_status' ), 1000 );
-
 		// Do not spawn cron (especially the alternate cron) while running the Customizer.
 		remove_action( 'init', 'wp_cron' );
 
@@ -340,7 +399,7 @@ final class WP_Customize_Manager {
 	 * @param mixed $message UI message
 	 */
 	protected function wp_die( $ajax_message, $message = null ) {
-		if ( $this->doing_ajax() || isset( $_POST['customized'] ) ) {
+		if ( $this->doing_ajax() ) {
 			wp_die( $ajax_message );
 		}
 
@@ -348,6 +407,29 @@ final class WP_Customize_Manager {
 			$message = __( 'Cheatin&#8217; uh?' );
 		}
 
+		if ( $this->messenger_channel ) {
+			ob_start();
+			wp_enqueue_scripts();
+			wp_print_scripts( array( 'customize-base' ) );
+
+			$settings = array(
+				'messengerArgs' => array(
+					'channel' => $this->messenger_channel,
+					'url' => wp_customize_url(),
+				),
+				'error' => $ajax_message,
+			);
+			?>
+			<script>
+			( function( api, settings ) {
+				var preview = new api.Messenger( settings.messengerArgs );
+				preview.send( 'iframe-loading-error', settings.error );
+			} )( wp.customize, <?php echo wp_json_encode( $settings ) ?> );
+			</script>
+			<?php
+			$message .= ob_get_clean();
+		}
+
 		wp_die( $message );
 	}
 
@@ -355,10 +437,13 @@ final class WP_Customize_Manager {
 	 * Return the Ajax wp_die() handler if it's a customized request.
 	 *
 	 * @since 3.4.0
+	 * @deprecated 4.7.0
 	 *
-	 * @return string
+	 * @return callable Die handler.
 	 */
 	public function wp_die_handler() {
+		_deprecated_function( __METHOD__, '4.7.0' );
+
 		if ( $this->doing_ajax() || isset( $_POST['customized'] ) ) {
 			return '_ajax_wp_die_handler';
 		}
@@ -374,24 +459,43 @@ final class WP_Customize_Manager {
 	 * @since 3.4.0
 	 */
 	public function setup_theme() {
-		send_origin_headers();
+		global $pagenow;
 
-		$doing_ajax_or_is_customized = ( $this->doing_ajax() || isset( $_POST['customized'] ) );
-		if ( is_admin() && ! $doing_ajax_or_is_customized ) {
-			auth_redirect();
-		} elseif ( $doing_ajax_or_is_customized && ! is_user_logged_in() ) {
-			$this->wp_die( 0, __( 'You must be logged in to complete this action.' ) );
+		// Check permissions for customize.php access since this method is called before customize.php can run any code,
+		if ( 'customize.php' === $pagenow && ! current_user_can( 'customize' ) ) {
+			if ( ! is_user_logged_in() ) {
+				auth_redirect();
+			} else {
+				wp_die(
+					'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1>' .
+					'<p>' . __( 'Sorry, you are not allowed to customize this site.' ) . '</p>',
+					403
+				);
+			}
+			return;
 		}
 
-		show_admin_bar( false );
-
-		if ( ! current_user_can( 'customize' ) ) {
-			$this->wp_die( -1, __( 'Sorry, you are not allowed to customize this site.' ) );
+		if ( ! preg_match( '/^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/', $this->_changeset_uuid ) ) {
+			$this->wp_die( -1, __( 'Invalid changeset UUID' ) );
 		}
 
-		$this->original_stylesheet = get_stylesheet();
+		/*
+		 * If unauthenticated then require a valid changeset UUID to load the preview.
+		 * In this way, the UUID serves as a secret key. If the messenger channel is present,
+		 * then send unauthenticated code to prompt re-auth.
+		 */
+		if ( ! current_user_can( 'customize' ) && ! $this->changeset_post_id() ) {
+			$this->wp_die( $this->messenger_channel ? 0 : -1, __( 'Non-existent changeset UUID.' ) );
+		}
 
-		$this->theme = wp_get_theme( isset( $_REQUEST['theme'] ) ? $_REQUEST['theme'] : null );
+		if ( ! headers_sent() ) {
+			send_origin_headers();
+		}
+
+		// Hide the admin bar if we're embedded in the customizer iframe.
+		if ( $this->messenger_channel ) {
+			show_admin_bar( false );
+		}
 
 		if ( $this->is_theme_active() ) {
 			// Once the theme is loaded, we'll validate it.
@@ -506,6 +610,18 @@ final class WP_Customize_Manager {
 		do_action( 'stop_previewing_theme', $this );
 	}
 
+	/**
+	 * Get the changeset UUID.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 *
+	 * @return string UUID.
+	 */
+	public function changeset_uuid() {
+		return $this->_changeset_uuid;
+	}
+
 	/**
 	 * Get the theme being customized.
 	 *
@@ -603,8 +719,23 @@ final class WP_Customize_Manager {
 		 */
 		do_action( 'customize_register', $this );
 
-		if ( $this->is_preview() && ! is_admin() )
+		/*
+		 * Note that settings must be previewed here even outside the customizer preview
+		 * and also in the customizer pane itself. This is to enable loading an existing
+		 * changeset into the customizer. Previewing the settings only has to be prevented
+		 * in the case of a customize_save action because then update_option()
+		 * may short-circuit because it will detect that there are no changes to
+		 * make.
+		 */
+		if ( ! $this->doing_ajax( 'customize_save' ) ) {
+			foreach ( $this->settings as $setting ) {
+				$setting->preview();
+			}
+		}
+
+		if ( $this->is_preview() && ! is_admin() ) {
 			$this->customize_preview_init();
+		}
 	}
 
 	/**
@@ -614,43 +745,224 @@ final class WP_Customize_Manager {
 	 * Instead, the JS will sniff out the location header.
 	 *
 	 * @since 3.4.0
+	 * @deprecated 4.7.0
 	 *
-	 * @param $status
+	 * @param int $status Status.
 	 * @return int
 	 */
 	public function wp_redirect_status( $status ) {
-		if ( $this->is_preview() && ! is_admin() )
+		_deprecated_function( __FUNCTION__, '4.7.0' );
+
+		if ( $this->is_preview() && ! is_admin() ) {
 			return 200;
+		}
 
 		return $status;
 	}
 
 	/**
-	 * Parse the incoming $_POST['customized'] JSON data and store the unsanitized
-	 * settings for subsequent post_value() lookups.
+	 * Find the changeset post ID for a given changeset UUID.
 	 *
-	 * @since 4.1.1
+	 * @since 4.7.0
+	 * @access public
 	 *
-	 * @return array
+	 * @param string $uuid Changeset UUID.
+	 * @return int|null Returns post ID on success and null on failure.
 	 */
-	public function unsanitized_post_values() {
-		if ( ! isset( $this->_post_values ) ) {
-			if ( isset( $_POST['customized'] ) ) {
-				$this->_post_values = json_decode( wp_unslash( $_POST['customized'] ), true );
-			}
-			if ( empty( $this->_post_values ) ) { // if not isset or if JSON error
-				$this->_post_values = array();
-			}
+	public function find_changeset_post_id( $uuid ) {
+		$cache_group = 'customize_changeset_post';
+		$changeset_post_id = wp_cache_get( $uuid, $cache_group );
+		if ( $changeset_post_id && 'customize_changeset' === get_post_type( $changeset_post_id ) ) {
+			return $changeset_post_id;
 		}
-		if ( empty( $this->_post_values ) ) {
-			return array();
-		} else {
-			return $this->_post_values;
+
+		$changeset_post_query = new WP_Query( array(
+			'post_type' => 'customize_changeset',
+			'post_status' => get_post_stati(),
+			'name' => $uuid,
+			'number' => 1,
+			'no_found_rows' => true,
+			'cache_results' => true,
+			'update_post_meta_cache' => false,
+			'update_term_meta_cache' => false,
+		) );
+		if ( ! empty( $changeset_post_query->posts ) ) {
+			// Note: 'fields'=>'ids' is not being used in order to cache the post object as it will be needed.
+			$changeset_post_id = $changeset_post_query->posts[0]->ID;
+			wp_cache_set( $this->_changeset_uuid, $changeset_post_id, $cache_group );
+			return $changeset_post_id;
 		}
+
+		return null;
 	}
 
 	/**
-	 * Returns the sanitized value for a given setting from the request's POST data.
+	 * Get the changeset post id for the loaded changeset.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 *
+	 * @return int|null Post ID on success or null if there is no post yet saved.
+	 */
+	public function changeset_post_id() {
+		if ( ! isset( $this->_changeset_post_id ) ) {
+			$post_id = $this->find_changeset_post_id( $this->_changeset_uuid );
+			if ( ! $post_id ) {
+				$post_id = false;
+			}
+			$this->_changeset_post_id = $post_id;
+		}
+		if ( false === $this->_changeset_post_id ) {
+			return null;
+		}
+		return $this->_changeset_post_id;
+	}
+
+	/**
+	 * Get the data stored in a changeset post.
+	 *
+	 * @since 4.7.0
+	 * @access protected
+	 *
+	 * @param int $post_id Changeset post ID.
+	 * @return array|WP_Error Changeset data or WP_Error on error.
+	 */
+	protected function get_changeset_post_data( $post_id ) {
+		if ( ! $post_id ) {
+			return new WP_Error( 'empty_post_id' );
+		}
+		$changeset_post = get_post( $post_id );
+		if ( ! $changeset_post ) {
+			return new WP_Error( 'missing_post' );
+		}
+		if ( 'customize_changeset' !== $changeset_post->post_type ) {
+			return new WP_Error( 'wrong_post_type' );
+		}
+		$changeset_data = json_decode( $changeset_post->post_content, true );
+		if ( function_exists( 'json_last_error' ) && json_last_error() ) {
+			return new WP_Error( 'json_parse_error', '', json_last_error() );
+		}
+		if ( ! is_array( $changeset_data ) ) {
+			return new WP_Error( 'expected_array' );
+		}
+		return $changeset_data;
+	}
+
+	/**
+	 * Get changeset data.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 *
+	 * @return array Changeset data.
+	 */
+	public function changeset_data() {
+		if ( isset( $this->_changeset_data ) ) {
+			return $this->_changeset_data;
+		}
+		$changeset_post_id = $this->changeset_post_id();
+		if ( ! $changeset_post_id ) {
+			$this->_changeset_data = array();
+		} else {
+			$data = $this->get_changeset_post_data( $changeset_post_id );
+			if ( ! is_wp_error( $data ) ) {
+				$this->_changeset_data = $data;
+			} else {
+				$this->_changeset_data = array();
+			}
+		}
+		return $this->_changeset_data;
+	}
+
+	/**
+	 * Get dirty pre-sanitized setting values in the current customized state.
+	 *
+	 * The returned array consists of a merge of three sources:
+	 * 1. If the theme is not currently active, then the base array is any stashed
+	 *    theme mods that were modified previously but never published.
+	 * 2. The values from the current changeset, if it exists.
+	 * 3. If the user can customize, the values parsed from the incoming
+	 *    `$_POST['customized']` JSON data.
+	 * 4. Any programmatically-set post values via `WP_Customize_Manager::set_post_value()`.
+	 *
+	 * The name "unsanitized_post_values" is a carry-over from when the customized
+	 * state was exclusively sourced from `$_POST['customized']`. Nevertheless,
+	 * the value returned will come from the current changeset post and from the
+	 * incoming post data.
+	 *
+	 * @since 4.1.1
+	 * @since 4.7.0 Added $args param and merging with changeset values and stashed theme mods.
+	 *
+	 * @param array $args {
+	 *     Args.
+	 *
+	 *     @type bool $exclude_changeset Whether the changeset values should also be excluded. Defaults to false.
+	 *     @type bool $exclude_post_data Whether the post input values should also be excluded. Defaults to false when lacking the customize capability.
+	 * }
+	 * @return array
+	 */
+	public function unsanitized_post_values( $args = array() ) {
+		$args = array_merge(
+			array(
+				'exclude_changeset' => false,
+				'exclude_post_data' => ! current_user_can( 'customize' ),
+			),
+			$args
+		);
+
+		$values = array();
+
+		// Let default values be from the stashed theme mods if doing a theme switch and if no changeset is present.
+		if ( ! $this->is_theme_active() ) {
+			$stashed_theme_mods = get_option( 'customize_stashed_theme_mods' );
+			$stylesheet = $this->get_stylesheet();
+			if ( isset( $stashed_theme_mods[ $stylesheet ] ) ) {
+				$values = array_merge( $values, wp_list_pluck( $stashed_theme_mods[ $stylesheet ], 'value' ) );
+			}
+		}
+
+		if ( ! $args['exclude_changeset'] ) {
+			foreach ( $this->changeset_data() as $setting_id => $setting_params ) {
+				if ( ! array_key_exists( 'value', $setting_params ) ) {
+					continue;
+				}
+				if ( isset( $setting_params['type'] ) && 'theme_mod' === $setting_params['type'] ) {
+
+					// Ensure that theme mods values are only used if they were saved under the current theme.
+					$namespace_pattern = '/^(?P<stylesheet>.+?)::(?P<setting_id>.+)$/';
+					if ( preg_match( $namespace_pattern, $setting_id, $matches ) && $this->get_stylesheet() === $matches['stylesheet'] ) {
+						$values[ $matches['setting_id'] ] = $setting_params['value'];
+					}
+				} else {
+					$values[ $setting_id ] = $setting_params['value'];
+				}
+			}
+		}
+
+		if ( ! $args['exclude_post_data'] ) {
+			if ( ! isset( $this->_post_values ) ) {
+				if ( isset( $_POST['customized'] ) ) {
+					$post_values = json_decode( wp_unslash( $_POST['customized'] ), true );
+				} else {
+					$post_values = array();
+				}
+				if ( is_array( $post_values ) ) {
+					$this->_post_values = $post_values;
+				} else {
+					$this->_post_values = array();
+				}
+			}
+			$values = array_merge( $values, $this->_post_values );
+		}
+		return $values;
+	}
+
+	/**
+	 * Returns the sanitized value for a given setting from the current customized state.
+	 *
+	 * The name "post_value" is a carry-over from when the customized state was exclusively
+	 * sourced from `$_POST['customized']`. Nevertheless, the value returned will come
+	 * from the current changeset post and from the incoming post data.
 	 *
 	 * @since 3.4.0
 	 * @since 4.1.1 Introduced the `$default` parameter.
@@ -684,7 +996,10 @@ final class WP_Customize_Manager {
 	}
 
 	/**
-	 * Override a setting's (unsanitized) value as found in any incoming $_POST['customized'].
+	 * Override a setting's value in the current customized state.
+	 *
+	 * The name "post_value" is a carry-over from when the customized state was
+	 * exclusively sourced from `$_POST['customized']`.
 	 *
 	 * @since 4.2.0
 	 * @access public
@@ -693,7 +1008,7 @@ final class WP_Customize_Manager {
 	 * @param mixed  $value      Post value.
 	 */
 	public function set_post_value( $setting_id, $value ) {
-		$this->unsanitized_post_values();
+		$this->unsanitized_post_values(); // Populate _post_values from $_POST['customized'].
 		$this->_post_values[ $setting_id ] = $value;
 
 		/**
@@ -733,21 +1048,39 @@ final class WP_Customize_Manager {
 	 * @since 3.4.0
 	 */
 	public function customize_preview_init() {
-		$this->nonce_tick = check_ajax_referer( 'preview-customize_' . $this->get_stylesheet(), 'nonce' );
+
+		/*
+		 * Now that Customizer previews are loaded into iframes via GET requests
+		 * and natural URLs with transaction UUIDs added, we need to ensure that
+		 * the responses are never cached by proxies. In practice, this will not
+		 * be needed if the user is logged-in anyway. But if anonymous access is
+		 * allowed then the auth cookies would not be sent and WordPress would
+		 * not send no-cache headers by default.
+		 */
+		if ( ! headers_sent() ) {
+			nocache_headers();
+			header( 'X-Robots: noindex, nofollow, noarchive' );
+		}
+		add_action( 'wp_head', 'wp_no_robots' );
+		add_filter( 'wp_headers', array( $this, 'filter_iframe_security_headers' ) );
+
+		/*
+		 * If preview is being served inside the customizer preview iframe, and
+		 * if the user doesn't have customize capability, then it is assumed
+		 * that the user's session has expired and they need to re-authenticate.
+		 */
+		if ( $this->messenger_channel && ! current_user_can( 'customize' ) ) {
+			$this->wp_die( -1, __( 'Unauthorized. You may remove the customize_messenger_channel param to preview as frontend.' ) );
+			return;
+		}
 
 		$this->prepare_controls();
 
+		add_filter( 'wp_redirect', array( $this, 'add_state_query_params' ) );
+
 		wp_enqueue_script( 'customize-preview' );
-		add_action( 'wp', array( $this, 'customize_preview_override_404_status' ) );
-		add_action( 'wp_head', array( $this, 'customize_preview_base' ) );
 		add_action( 'wp_head', array( $this, 'customize_preview_loading_style' ) );
 		add_action( 'wp_footer', array( $this, 'customize_preview_settings' ), 20 );
-		add_action( 'shutdown', array( $this, 'customize_preview_signature' ), 1000 );
-		add_filter( 'wp_die_handler', array( $this, 'remove_preview_signature' ) );
-
-		foreach ( $this->settings as $setting ) {
-			$setting->preview();
-		}
 
 		/**
 		 * Fires once the Customizer preview has initialized and JavaScript
@@ -760,26 +1093,86 @@ final class WP_Customize_Manager {
 		do_action( 'customize_preview_init', $this );
 	}
 
+	/**
+	 * Filter the X-Frame-Options and Content-Security-Policy headers to ensure frontend can load in customizer.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 *
+	 * @param array $headers Headers.
+	 * @return array Headers.
+	 */
+	public function filter_iframe_security_headers( $headers ) {
+		$customize_url = admin_url( 'customize.php' );
+		$headers['X-Frame-Options'] = 'ALLOW-FROM ' . $customize_url;
+		$headers['Content-Security-Policy'] = 'frame-ancestors ' . preg_replace( '#^(\w+://[^/]+).+?$#', '$1', $customize_url );
+		return $headers;
+	}
+
+	/**
+	 * Add customize state query params to a given URL if preview is allowed.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 * @see wp_redirect()
+	 * @see WP_Customize_Manager::get_allowed_url()
+	 *
+	 * @param string $url URL.
+	 * @return string URL.
+	 */
+	public function add_state_query_params( $url ) {
+		$parsed_original_url = wp_parse_url( $url );
+		$is_allowed = false;
+		foreach ( $this->get_allowed_urls() as $allowed_url ) {
+			$parsed_allowed_url = wp_parse_url( $allowed_url );
+			$is_allowed = (
+				$parsed_allowed_url['scheme'] === $parsed_original_url['scheme']
+				&&
+				$parsed_allowed_url['host'] === $parsed_original_url['host']
+				&&
+				0 === strpos( $parsed_original_url['path'], $parsed_allowed_url['path'] )
+			);
+			if ( $is_allowed ) {
+				break;
+			}
+		}
+
+		if ( $is_allowed ) {
+			$query_params = array(
+				'customize_changeset_uuid' => $this->changeset_uuid(),
+			);
+			if ( ! $this->is_theme_active() ) {
+				$query_params['customize_theme'] = $this->get_stylesheet();
+			}
+			if ( $this->messenger_channel ) {
+				$query_params['customize_messenger_channel'] = $this->messenger_channel;
+			}
+			$url = add_query_arg( $query_params, $url );
+		}
+
+		return $url;
+	}
+
 	/**
 	 * Prevent sending a 404 status when returning the response for the customize
 	 * preview, since it causes the jQuery Ajax to fail. Send 200 instead.
 	 *
 	 * @since 4.0.0
+	 * @deprecated 4.7.0
 	 * @access public
 	 */
 	public function customize_preview_override_404_status() {
-		if ( is_404() ) {
-			status_header( 200 );
-		}
+		_deprecated_function( __METHOD__, '4.7.0' );
 	}
 
 	/**
 	 * Print base element for preview frame.
 	 *
 	 * @since 3.4.0
+	 * @deprecated 4.7.0
 	 */
 	public function customize_preview_base() {
-		?><base href="<?php echo home_url( '/' ); ?>" /><?php
+		_deprecated_function( __METHOD__, '4.7.0' );
 	}
 
 	/**
@@ -809,6 +1202,14 @@ final class WP_Customize_Manager {
 			body.wp-customizer-unloading * {
 				pointer-events: none !important;
 			}
+			form.customize-unpreviewable,
+			form.customize-unpreviewable input,
+			form.customize-unpreviewable select,
+			form.customize-unpreviewable button,
+			a.customize-unpreviewable,
+			area.customize-unpreviewable {
+				cursor: not-allowed !important;
+			}
 		</style><?php
 	}
 
@@ -818,27 +1219,62 @@ final class WP_Customize_Manager {
 	 * @since 3.4.0
 	 */
 	public function customize_preview_settings() {
-		$setting_validities = $this->validate_setting_values( $this->unsanitized_post_values() );
+		$post_values = $this->unsanitized_post_values( array( 'exclude_changeset' => true ) );
+		$setting_validities = $this->validate_setting_values( $post_values );
 		$exported_setting_validities = array_map( array( $this, 'prepare_setting_validity_for_js' ), $setting_validities );
 
+		// Note that the REQUEST_URI is not passed into home_url() since this breaks subdirectory installs.
+		$self_url = empty( $_SERVER['REQUEST_URI'] ) ? home_url( '/' ) : esc_url_raw( wp_unslash( $_SERVER['REQUEST_URI'] ) );
+		$state_query_params = array(
+			'customize_theme',
+			'customize_changeset_uuid',
+			'customize_messenger_channel',
+		);
+		$self_url = remove_query_arg( $state_query_params, $self_url );
+
+		$allowed_urls = $this->get_allowed_urls();
+		$allowed_hosts = array();
+		foreach ( $allowed_urls as $allowed_url ) {
+			$parsed = wp_parse_url( $allowed_url );
+			if ( empty( $parsed['host'] ) ) {
+				continue;
+			}
+			$host = $parsed['host'];
+			if ( ! empty( $parsed['port'] ) ) {
+				$host .= ':' . $parsed['port'];
+			}
+			$allowed_hosts[] = $host;
+		}
 		$settings = array(
+			'changeset' => array(
+				'uuid' => $this->_changeset_uuid,
+			),
+			'timeouts' => array(
+				'selectiveRefresh' => 250,
+				'keepAliveSend' => 1000,
+			),
 			'theme' => array(
 				'stylesheet' => $this->get_stylesheet(),
 				'active'     => $this->is_theme_active(),
 			),
 			'url' => array(
-				'self' => empty( $_SERVER['REQUEST_URI'] ) ? home_url( '/' ) : esc_url_raw( wp_unslash( $_SERVER['REQUEST_URI'] ) ),
+				'self' => $self_url,
+				'allowed' => array_map( 'esc_url_raw', $this->get_allowed_urls() ),
+				'allowedHosts' => array_unique( $allowed_hosts ),
+				'isCrossDomain' => $this->is_cross_domain(),
 			),
-			'channel' => wp_unslash( $_POST['customize_messenger_channel'] ),
+			'channel' => $this->messenger_channel,
 			'activePanels' => array(),
 			'activeSections' => array(),
 			'activeControls' => array(),
 			'settingValidities' => $exported_setting_validities,
-			'nonce' => $this->get_nonces(),
+			'nonce' => current_user_can( 'customize' ) ? $this->get_nonces() : array(),
 			'l10n' => array(
 				'shiftClickToEdit' => __( 'Shift-click to edit this element.' ),
+				'linkUnpreviewable' => __( 'This link is not live-previewable.' ),
+				'formUnpreviewable' => __( 'This form is not live-previewable.' ),
 			),
-			'_dirty' => array_keys( $this->unsanitized_post_values() ),
+			'_dirty' => array_keys( $post_values ),
 		);
 
 		foreach ( $this->panels as $panel_id => $panel ) {
@@ -892,21 +1328,23 @@ final class WP_Customize_Manager {
 	 * Prints a signature so we can ensure the Customizer was properly executed.
 	 *
 	 * @since 3.4.0
+	 * @deprecated 4.7.0
 	 */
 	public function customize_preview_signature() {
-		echo 'WP_CUSTOMIZER_SIGNATURE';
+		_deprecated_function( __METHOD__, '4.7.0' );
 	}
 
 	/**
 	 * Removes the signature in case we experience a case where the Customizer was not properly executed.
 	 *
 	 * @since 3.4.0
+	 * @deprecated 4.7.0
 	 *
 	 * @param mixed $return Value passed through for {@see 'wp_die_handler'} filter.
 	 * @return mixed Value passed through for {@see 'wp_die_handler'} filter.
 	 */
 	public function remove_preview_signature( $return = null ) {
-		remove_action( 'shutdown', array( $this, 'customize_preview_signature' ), 1000 );
+		_deprecated_function( __METHOD__, '4.7.0' );
 
 		return $return;
 	}
@@ -993,16 +1431,37 @@ final class WP_Customize_Manager {
 	 * @see WP_Customize_Setting::validate()
 	 *
 	 * @param array $setting_values Mapping of setting IDs to values to validate and sanitize.
+	 * @param array $options {
+	 *     Options.
+	 *
+	 *     @type bool $validate_existence  Whether a setting's existence will be checked.
+	 *     @type bool $validate_capability Whether the setting capability will be checked.
+	 * }
 	 * @return array Mapping of setting IDs to return value of validate method calls, either `true` or `WP_Error`.
 	 */
-	public function validate_setting_values( $setting_values ) {
+	public function validate_setting_values( $setting_values, $options = array() ) {
+		$options = wp_parse_args( $options, array(
+			'validate_capability' => false,
+			'validate_existence' => false,
+		) );
+
 		$validities = array();
 		foreach ( $setting_values as $setting_id => $unsanitized_value ) {
 			$setting = $this->get_setting( $setting_id );
-			if ( ! $setting || is_null( $unsanitized_value ) ) {
+			if ( ! $setting ) {
+				if ( $options['validate_existence'] ) {
+					$validities[ $setting_id ] = new WP_Error( 'unrecognized', __( 'Setting does not exist or is unrecognized.' ) );
+				}
 				continue;
 			}
-			$validity = $setting->validate( $unsanitized_value );
+			if ( is_null( $unsanitized_value ) ) {
+				continue;
+			}
+			if ( $options['validate_capability'] && ! current_user_can( $setting->capability ) ) {
+				$validity = new WP_Error( 'unauthorized', __( 'Unauthorized to modify setting due to capability.' ) );
+			} else {
+				$validity = $setting->validate( $unsanitized_value );
+			}
 			if ( ! is_wp_error( $validity ) ) {
 				/** This filter is documented in wp-includes/class-wp-customize-setting.php */
 				$late_validity = apply_filters( "customize_validate_{$setting->id}", new WP_Error(), $unsanitized_value, $setting );
@@ -1056,11 +1515,16 @@ final class WP_Customize_Manager {
 	}
 
 	/**
-	 * Switch the theme and trigger the save() method on each setting.
+	 * Handle customize_save WP Ajax request to save/update a changeset.
 	 *
 	 * @since 3.4.0
+	 * @since 4.7.0 The semantics of this method have changed to update a changeset, optionally to also change the status and other attributes.
 	 */
 	public function save() {
+		if ( ! is_user_logged_in() ) {
+			wp_send_json_error( 'unauthenticated' );
+		}
+
 		if ( ! $this->is_preview() ) {
 			wp_send_json_error( 'not_preview' );
 		}
@@ -1070,6 +1534,191 @@ final class WP_Customize_Manager {
 			wp_send_json_error( 'invalid_nonce' );
 		}
 
+		$changeset_post_id = $this->changeset_post_id();
+		if ( $changeset_post_id && in_array( get_post_status( $changeset_post_id ), array( 'publish', 'trash' ) ) ) {
+			wp_send_json_error( 'changeset_already_published' );
+		}
+
+		if ( empty( $changeset_post_id ) ) {
+			if ( ! current_user_can( get_post_type_object( 'customize_changeset' )->cap->create_posts ) ) {
+				wp_send_json_error( 'cannot_create_changeset_post' );
+			}
+		} else {
+			if ( ! current_user_can( get_post_type_object( 'customize_changeset' )->cap->edit_post, $changeset_post_id ) ) {
+				wp_send_json_error( 'cannot_edit_changeset_post' );
+			}
+		}
+
+		if ( ! empty( $_POST['customize_changeset_data'] ) ) {
+			$input_changeset_data = json_decode( wp_unslash( $_POST['customize_changeset_data'] ), true );
+			if ( ! is_array( $input_changeset_data ) ) {
+				wp_send_json_error( 'invalid_customize_changeset_data' );
+			}
+		} else {
+			$input_changeset_data = array();
+		}
+
+		// Validate title.
+		$changeset_title = null;
+		if ( isset( $_POST['customize_changeset_title'] ) ) {
+			$changeset_title = sanitize_text_field( wp_unslash( $_POST['customize_changeset_title'] ) );
+		}
+
+		// Validate changeset status param.
+		$is_publish = null;
+		$changeset_status = null;
+		if ( isset( $_POST['customize_changeset_status'] ) ) {
+			$changeset_status = wp_unslash( $_POST['customize_changeset_status'] );
+			if ( ! get_post_status_object( $changeset_status ) || ! in_array( $changeset_status, array( 'draft', 'pending', 'publish', 'future' ), true ) ) {
+				wp_send_json_error( 'bad_customize_changeset_status', 400 );
+			}
+			$is_publish = ( 'publish' === $changeset_status || 'future' === $changeset_status );
+			if ( $is_publish ) {
+				if ( ! current_user_can( get_post_type_object( 'customize_changeset' )->cap->publish_posts ) ) {
+					wp_send_json_error( 'changeset_publish_unauthorized', 403 );
+				}
+				if ( false === has_action( 'transition_post_status', '_wp_customize_publish_changeset' ) ) {
+					wp_send_json_error( 'missing_publish_callback', 500 );
+				}
+			}
+		}
+
+		/*
+		 * Validate changeset date param. Date is assumed to be in local time for
+		 * the WP if in MySQL format (YYYY-MM-DD HH:MM:SS). Otherwise, the date
+		 * is parsed with strtotime() so that ISO date format may be supplied
+		 * or a string like "+10 minutes".
+		 */
+		$changeset_date_gmt = null;
+		if ( isset( $_POST['customize_changeset_date'] ) ) {
+			$changeset_date = wp_unslash( $_POST['customize_changeset_date'] );
+			if ( preg_match( '/^\d\d\d\d-\d\d-\d\d \d\d:\d\d:\d\d$/', $changeset_date ) ) {
+				$mm = substr( $changeset_date, 5, 2 );
+				$jj = substr( $changeset_date, 8, 2 );
+				$aa = substr( $changeset_date, 0, 4 );
+				$valid_date = wp_checkdate( $mm, $jj, $aa, $changeset_date );
+				if ( ! $valid_date ) {
+					wp_send_json_error( 'bad_customize_changeset_date', 400 );
+				}
+				$changeset_date_gmt = get_gmt_from_date( $changeset_date );
+			} else {
+				$timestamp = strtotime( $changeset_date );
+				if ( ! $timestamp ) {
+					wp_send_json_error( 'bad_customize_changeset_date', 400 );
+				}
+				$changeset_date_gmt = gmdate( 'Y-m-d H:i:s', $timestamp );
+			}
+			$now = gmdate( 'Y-m-d H:i:59' );
+
+			$is_future_dated = ( mysql2date( 'U', $changeset_date_gmt, false ) > mysql2date( 'U', $now, false ) );
+			if ( ! $is_future_dated ) {
+				wp_send_json_error( 'not_future_date', 400 ); // Only future dates are allowed.
+			}
+
+			if ( ! $this->is_theme_active() && ( 'future' === $changeset_status || $is_future_dated ) ) {
+				wp_send_json_error( 'cannot_schedule_theme_switches', 400 ); // This should be allowed in the future, when theme is a regular setting.
+			}
+			$will_remain_auto_draft = ( ! $changeset_status && ( ! $changeset_post_id || 'auto-draft' === get_post_status( $changeset_post_id ) ) );
+			if ( $changeset_date && $will_remain_auto_draft ) {
+				wp_send_json_error( 'cannot_supply_date_for_auto_draft_changeset', 400 );
+			}
+		}
+
+		$r = $this->save_changeset_post( array(
+			'status' => $changeset_status,
+			'title' => $changeset_title,
+			'date_gmt' => $changeset_date_gmt,
+			'data' => $input_changeset_data,
+		) );
+		if ( is_wp_error( $r ) ) {
+			$response = $r->get_error_data();
+		} else {
+			$response = $r;
+
+			// Note that if the changeset status was publish, then it will get set to trash if revisions are not supported.
+			$response['changeset_status'] = get_post_status( $this->changeset_post_id() );
+			if ( $is_publish && 'trash' === $response['changeset_status'] ) {
+				$response['changeset_status'] = 'publish';
+			}
+
+			if ( 'publish' === $response['changeset_status'] ) {
+				$response['next_changeset_uuid'] = wp_generate_uuid4();
+			}
+		}
+
+		if ( isset( $response['setting_validities'] ) ) {
+			$response['setting_validities'] = array_map( array( $this, 'prepare_setting_validity_for_js' ), $response['setting_validities'] );
+		}
+
+		/**
+		 * Filters response data for a successful customize_save Ajax request.
+		 *
+		 * This filter does not apply if there was a nonce or authentication failure.
+		 *
+		 * @since 4.2.0
+		 *
+		 * @param array                $response Additional information passed back to the 'saved'
+		 *                                       event on `wp.customize`.
+		 * @param WP_Customize_Manager $this     WP_Customize_Manager instance.
+		 */
+		$response = apply_filters( 'customize_save_response', $response, $this );
+
+		if ( is_wp_error( $r ) ) {
+			wp_send_json_error( $response );
+		} else {
+			wp_send_json_success( $response );
+		}
+	}
+
+	/**
+	 * Save the post for the loaded changeset.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 *
+	 * @param array $args {
+	 *     Args for changeset post.
+	 *
+	 *     @type array  $data     Optional additional changeset data. Values will be merged on top of any existing post values.
+	 *     @type string $status   Post status. Optional. If supplied, the save will be transactional and a post revision will be allowed.
+	 *     @type string $title    Post title. Optional.
+	 *     @type string $date_gmt Date in GMT. Optional.
+	 * }
+	 *
+	 * @return array|WP_Error Returns array on success and WP_Error with array data on error.
+	 */
+	function save_changeset_post( $args = array() ) {
+
+		$args = array_merge(
+			array(
+				'status' => null,
+				'title' => null,
+				'data' => array(),
+				'date_gmt' => null,
+			),
+			$args
+		);
+
+		$changeset_post_id = $this->changeset_post_id();
+
+		// The request was made via wp.customize.previewer.save().
+		$update_transactionally = (bool) $args['status'];
+		$allow_revision = (bool) $args['status'];
+
+		// Amend post values with any supplied data.
+		foreach ( $args['data'] as $setting_id => $setting_params ) {
+			if ( array_key_exists( 'value', $setting_params ) ) {
+				$this->set_post_value( $setting_id, $setting_params['value'] ); // Add to post values so that they can be validated and sanitized.
+			}
+		}
+
+		// Note that in addition to post data, this will include any stashed theme mods.
+		$post_values = $this->unsanitized_post_values( array(
+			'exclude_changeset' => true,
+			'exclude_post_data' => false,
+		) );
+		$this->add_dynamic_settings( array_keys( $post_values ) ); // Ensure settings get created even if they lack an input value.
+
 		/**
 		 * Fires before save validation happens.
 		 *
@@ -1084,42 +1733,318 @@ final class WP_Customize_Manager {
 		do_action( 'customize_save_validation_before', $this );
 
 		// Validate settings.
-		$setting_validities = $this->validate_setting_values( $this->unsanitized_post_values() );
+		$setting_validities = $this->validate_setting_values( $post_values, array(
+			'validate_capability' => true,
+			'validate_existence' => true,
+		) );
 		$invalid_setting_count = count( array_filter( $setting_validities, 'is_wp_error' ) );
-		$exported_setting_validities = array_map( array( $this, 'prepare_setting_validity_for_js' ), $setting_validities );
-		if ( $invalid_setting_count > 0 ) {
+
+		/*
+		 * Short-circuit if there are invalid settings the update is transactional.
+		 * A changeset update is transactional when a status is supplied in the request.
+		 */
+		if ( $update_transactionally && $invalid_setting_count > 0 ) {
 			$response = array(
-				'setting_validities' => $exported_setting_validities,
+				'setting_validities' => $setting_validities,
 				'message' => sprintf( _n( 'There is %s invalid setting.', 'There are %s invalid settings.', $invalid_setting_count ), number_format_i18n( $invalid_setting_count ) ),
 			);
-
-			/** This filter is documented in wp-includes/class-wp-customize-manager.php */
-			$response = apply_filters( 'customize_save_response', $response, $this );
-			wp_send_json_error( $response );
+			return new WP_Error( 'transaction_fail', '', $response );
 		}
 
-		// Do we have to switch themes?
-		if ( ! $this->is_theme_active() ) {
-			// Temporarily stop previewing the theme to allow switch_themes()
-			// to operate properly.
+		$response = array(
+			'setting_validities' => $setting_validities,
+		);
+
+		// Obtain/merge data for changeset.
+		$original_changeset_data = $this->get_changeset_post_data( $changeset_post_id );
+		$data = $original_changeset_data;
+		if ( is_wp_error( $data ) ) {
+			$data = array();
+		}
+
+		// Ensure that all post values are included in the changeset data.
+		foreach ( $post_values as $setting_id => $post_value ) {
+			if ( ! isset( $args['data'][ $setting_id ] ) ) {
+				$args['data'][ $setting_id ] = array();
+			}
+			if ( ! isset( $args['data'][ $setting_id ]['value'] ) ) {
+				$args['data'][ $setting_id ]['value'] = $post_value;
+			}
+		}
+
+		foreach ( $args['data'] as $setting_id => $setting_params ) {
+			$setting = $this->get_setting( $setting_id );
+			if ( ! $setting || ! $setting->check_capabilities() ) {
+				continue;
+			}
+
+			// Skip updating changeset for invalid setting values.
+			if ( isset( $setting_validities[ $setting_id ] ) && is_wp_error( $setting_validities[ $setting_id ] ) ) {
+				continue;
+			}
+
+			$changeset_setting_id = $setting_id;
+			if ( 'theme_mod' === $setting->type ) {
+				$changeset_setting_id = sprintf( '%s::%s', $this->get_stylesheet(), $setting_id );
+			}
+
+			if ( null === $setting_params ) {
+				// Remove setting from changeset entirely.
+				unset( $data[ $changeset_setting_id ] );
+			} else {
+				// Merge any additional setting params that have been supplied with the existing params.
+				if ( ! isset( $data[ $changeset_setting_id ] ) ) {
+					$data[ $changeset_setting_id ] = array();
+				}
+				$data[ $changeset_setting_id ] = array_merge(
+					$data[ $changeset_setting_id ],
+					$setting_params,
+					array( 'type' => $setting->type )
+				);
+			}
+		}
+
+		$filter_context = array(
+			'uuid' => $this->changeset_uuid(),
+			'title' => $args['title'],
+			'status' => $args['status'],
+			'date_gmt' => $args['date_gmt'],
+			'post_id' => $changeset_post_id,
+			'previous_data' => is_wp_error( $original_changeset_data ) ? array() : $original_changeset_data,
+			'manager' => $this,
+		);
+
+		/**
+		 * Filters the settings' data that will be persisted into the changeset.
+		 *
+		 * Plugins may amend additional data (such as additional meta for settings) into the changeset with this filter.
+		 *
+		 * @since 4.7.0
+		 *
+		 * @param array $data Updated changeset data, mapping setting IDs to arrays containing a $value item and optionally other metadata.
+		 * @param array $context {
+		 *     Filter context.
+		 *
+		 *     @type string               $uuid          Changeset UUID.
+		 *     @type string               $title         Requested title for the changeset post.
+		 *     @type string               $status        Requested status for the changeset post.
+		 *     @type string               $date_gmt      Requested date for the changeset post in MySQL format and GMT timezone.
+		 *     @type int|false            $post_id       Post ID for the changeset, or false if it doesn't exist yet.
+		 *     @type array                $previous_data Previous data contained in the changeset.
+		 *     @type WP_Customize_Manager $manager       Manager instance.
+		 * }
+		 */
+		$data = apply_filters( 'customize_changeset_save_data', $data, $filter_context );
+
+		// Switch theme if publishing changes now.
+		if ( 'publish' === $args['status'] && ! $this->is_theme_active() ) {
+			// Temporarily stop previewing the theme to allow switch_themes() to operate properly.
 			$this->stop_previewing_theme();
 			switch_theme( $this->get_stylesheet() );
 			update_option( 'theme_switched_via_customizer', true );
 			$this->start_previewing_theme();
 		}
 
+		// Gather the data for wp_insert_post()/wp_update_post().
+		$json_options = 0;
+		if ( defined( 'JSON_UNESCAPED_SLASHES' ) ) {
+			$json_options |= JSON_UNESCAPED_SLASHES; // Introduced in PHP 5.4. This is only to improve readability as slashes needn't be escaped in storage.
+		}
+		$json_options |= JSON_PRETTY_PRINT; // Also introduced in PHP 5.4, but WP defines constant for back compat. See WP Trac #30139.
+		$post_array = array(
+			'post_content' => wp_json_encode( $data, $json_options ),
+		);
+		if ( $args['title'] ) {
+			$post_array['post_title'] = $args['title'];
+		}
+		if ( $changeset_post_id ) {
+			$post_array['ID'] = $changeset_post_id;
+		} else {
+			$post_array['post_type'] = 'customize_changeset';
+			$post_array['post_name'] = $this->changeset_uuid();
+			$post_array['post_status'] = 'auto-draft';
+		}
+		if ( $args['status'] ) {
+			$post_array['post_status'] = $args['status'];
+		}
+		if ( $args['date_gmt'] ) {
+			$post_array['post_date_gmt'] = $args['date_gmt'];
+			$post_array['post_date'] = get_date_from_gmt( $args['date_gmt'] );
+		}
+
+		$this->store_changeset_revision = $allow_revision;
+		add_filter( 'wp_save_post_revision_post_has_changed', array( $this, '_filter_revision_post_has_changed' ), 5, 3 );
+
+		// Update the changeset post. The publish_customize_changeset action will cause the settings in the changeset to be saved via WP_Customize_Setting::save().
+		$has_kses = ( false !== has_filter( 'content_save_pre', 'wp_filter_post_kses' ) );
+		if ( $has_kses ) {
+			kses_remove_filters(); // Prevent KSES from corrupting JSON in post_content.
+		}
+
+		// Note that updating a post with publish status will trigger WP_Customize_Manager::publish_changeset_values().
+		if ( $changeset_post_id ) {
+			$post_array['edit_date'] = true; // Prevent date clearing.
+			$r = wp_update_post( wp_slash( $post_array ), true );
+		} else {
+			$r = wp_insert_post( wp_slash( $post_array ), true );
+			if ( ! is_wp_error( $r ) ) {
+				$this->_changeset_post_id = $r; // Update cached post ID for the loaded changeset.
+			}
+		}
+		if ( $has_kses ) {
+			kses_init_filters();
+		}
+		$this->_changeset_data = null; // Reset so WP_Customize_Manager::changeset_data() will re-populate with updated contents.
+
+		remove_filter( 'wp_save_post_revision_post_has_changed', array( $this, '_filter_revision_post_has_changed' ) );
+
+		if ( is_wp_error( $r ) ) {
+			$response['changeset_post_save_failure'] = $r->get_error_code();
+			return new WP_Error( 'changeset_post_save_failure', '', $response );
+		}
+
+		return $response;
+	}
+
+	/**
+	 * Whether a changeset revision should be made.
+	 *
+	 * @since 4.7.0
+	 * @access private
+	 * @var bool
+	 */
+	protected $store_changeset_revision;
+
+	/**
+	 * Filters whether a changeset has changed to create a new revision.
+	 *
+	 * Note that this will not be called while a changeset post remains in auto-draft status.
+	 *
+	 * @since 4.7.0
+	 * @access private
+	 *
+	 * @param bool    $post_has_changed Whether the post has changed.
+	 * @param WP_Post $last_revision    The last revision post object.
+	 * @param WP_Post $post             The post object.
+	 *
+	 * @return bool Whether a revision should be made.
+	 */
+	public function _filter_revision_post_has_changed( $post_has_changed, $last_revision, $post ) {
+		unset( $last_revision );
+		if ( 'customize_changeset' === $post->post_type ) {
+			$post_has_changed = $this->store_changeset_revision;
+		}
+		return $post_has_changed;
+	}
+
+	/**
+	 * Publish changeset values.
+	 *
+	 * This will the values contained in a changeset, even changesets that do not
+	 * correspond to current manager instance. This is called by
+	 * `_wp_customize_publish_changeset()` when a customize_changeset post is
+	 * transitioned to the `publish` status. As such, this method should not be
+	 * called directly and instead `wp_publish_post()` should be used.
+	 *
+	 * Please note that if the settings in the changeset are for a non-activated
+	 * theme, the theme must first be switched to (via `switch_theme()`) before
+	 * invoking this method.
+	 *
+	 * @since 4.7.0
+	 * @access private
+	 * @see _wp_customize_publish_changeset()
+	 *
+	 * @param int $changeset_post_id ID for customize_changeset post. Defaults to the changeset for the current manager instance.
+	 * @return true|WP_Error True or error info.
+	 */
+	public function _publish_changeset_values( $changeset_post_id ) {
+		$publishing_changeset_data = $this->get_changeset_post_data( $changeset_post_id );
+		if ( is_wp_error( $publishing_changeset_data ) ) {
+			return $publishing_changeset_data;
+		}
+
+		$changeset_post = get_post( $changeset_post_id );
+
+		/*
+		 * Temporarily override the changeset context so that it will be read
+		 * in calls to unsanitized_post_values() and so that it will be available
+		 * on the $wp_customize object passed to hooks during the save logic.
+		 */
+		$previous_changeset_post_id = $this->_changeset_post_id;
+		$this->_changeset_post_id   = $changeset_post_id;
+		$previous_changeset_uuid    = $this->_changeset_uuid;
+		$this->_changeset_uuid      = $changeset_post->post_name;
+		$previous_changeset_data    = $this->_changeset_data;
+		$this->_changeset_data      = $publishing_changeset_data;
+
+		// Ensure that other theme mods are stashed.
+		$other_theme_mod_settings = array();
+		if ( did_action( 'switch_theme' ) ) {
+			$namespace_pattern = '/^(?P<stylesheet>.+?)::(?P<setting_id>.+)$/';
+			$matches = array();
+			foreach ( $this->_changeset_data as $raw_setting_id => $setting_params ) {
+				$is_other_theme_mod = (
+					isset( $setting_params['value'] )
+					&&
+					isset( $setting_params['type'] )
+					&&
+					'theme_mod' === $setting_params['type']
+					&&
+					preg_match( $namespace_pattern, $raw_setting_id, $matches )
+					&&
+					$this->get_stylesheet() !== $matches['stylesheet']
+				);
+				if ( $is_other_theme_mod ) {
+					if ( ! isset( $other_theme_mod_settings[ $matches['stylesheet'] ] ) ) {
+						$other_theme_mod_settings[ $matches['stylesheet'] ] = array();
+					}
+					$other_theme_mod_settings[ $matches['stylesheet'] ][ $matches['setting_id'] ] = $setting_params;
+				}
+			}
+		}
+
+		$changeset_setting_values = $this->unsanitized_post_values( array(
+			'exclude_post_data' => true,
+			'exclude_changeset' => false,
+		) );
+		$changeset_setting_ids = array_keys( $changeset_setting_values );
+		$this->add_dynamic_settings( $changeset_setting_ids );
+
 		/**
 		 * Fires once the theme has switched in the Customizer, but before settings
 		 * have been saved.
 		 *
 		 * @since 3.4.0
 		 *
-		 * @param WP_Customize_Manager $this WP_Customize_Manager instance.
+		 * @param WP_Customize_Manager $manager WP_Customize_Manager instance.
 		 */
 		do_action( 'customize_save', $this );
 
-		foreach ( $this->settings as $setting ) {
-			$setting->save();
+		/*
+		 * Ensure that all settings will allow themselves to be saved. Note that
+		 * this is safe because the setting would have checked the capability
+		 * when the setting value was written into the changeset. So this is why
+		 * an additional capability check is not required here.
+		 */
+		$original_setting_capabilities = array();
+		foreach ( $changeset_setting_ids as $setting_id ) {
+			$setting = $this->get_setting( $setting_id );
+			if ( $setting ) {
+				$original_setting_capabilities[ $setting->id ] = $setting->capability;
+				$setting->capability = 'exist';
+			}
+		}
+
+		foreach ( $changeset_setting_ids as $setting_id ) {
+			$setting = $this->get_setting( $setting_id );
+			if ( $setting ) {
+				$setting->save();
+			}
+		}
+
+		// Update the stashed theme mod settings, removing the active theme's stashed settings, if activated.
+		if ( did_action( 'switch_theme' ) ) {
+			$this->update_stashed_theme_mod_settings( $other_theme_mod_settings );
 		}
 
 		/**
@@ -1127,27 +2052,62 @@ final class WP_Customize_Manager {
 		 *
 		 * @since 3.6.0
 		 *
-		 * @param WP_Customize_Manager $this WP_Customize_Manager instance.
+		 * @param WP_Customize_Manager $manager WP_Customize_Manager instance.
 		 */
 		do_action( 'customize_save_after', $this );
 
-		$data = array(
-			'setting_validities' => $exported_setting_validities,
-		);
+		// Restore original capabilities.
+		foreach ( $original_setting_capabilities as $setting_id => $capability ) {
+			$setting = $this->get_setting( $setting_id );
+			if ( $setting ) {
+				$setting->capability = $capability;
+			}
+		}
 
-		/**
-		 * Filters response data for a successful customize_save Ajax request.
-		 *
-		 * This filter does not apply if there was a nonce or authentication failure.
-		 *
-		 * @since 4.2.0
-		 *
-		 * @param array                $data Additional information passed back to the 'saved'
-		 *                                   event on `wp.customize`.
-		 * @param WP_Customize_Manager $this WP_Customize_Manager instance.
-		 */
-		$response = apply_filters( 'customize_save_response', $data, $this );
-		wp_send_json_success( $response );
+		// Restore original changeset data.
+		$this->_changeset_data    = $previous_changeset_data;
+		$this->_changeset_post_id = $previous_changeset_post_id;
+		$this->_changeset_uuid    = $previous_changeset_uuid;
+
+		return true;
+	}
+
+	/**
+	 * Update stashed theme mod settings.
+	 *
+	 * @since 4.7.0
+	 * @access private
+	 *
+	 * @param array $inactive_theme_mod_settings Mapping of stylesheet to arrays of theme mod settings.
+	 * @return array|false Returns array of updated stashed theme mods or false if the update failed or there were no changes.
+	 */
+	protected function update_stashed_theme_mod_settings( $inactive_theme_mod_settings ) {
+		$stashed_theme_mod_settings = get_option( 'customize_stashed_theme_mods' );
+		if ( empty( $stashed_theme_mod_settings ) ) {
+			$stashed_theme_mod_settings = array();
+		}
+
+		// Delete any stashed theme mods for the active theme since since they would have been loaded and saved upon activation.
+		unset( $stashed_theme_mod_settings[ $this->get_stylesheet() ] );
+
+		// Merge inactive theme mods with the stashed theme mod settings.
+		foreach ( $inactive_theme_mod_settings as $stylesheet => $theme_mod_settings ) {
+			if ( ! isset( $stashed_theme_mod_settings[ $stylesheet ] ) ) {
+				$stashed_theme_mod_settings[ $stylesheet ] = array();
+			}
+
+			$stashed_theme_mod_settings[ $stylesheet ] = array_merge(
+				$stashed_theme_mod_settings[ $stylesheet ],
+				$theme_mod_settings
+			);
+		}
+
+		$autoload = false;
+		$result = update_option( 'customize_stashed_theme_mods', $stashed_theme_mod_settings, $autoload );
+		if ( ! $result ) {
+			return false;
+		}
+		return $stashed_theme_mod_settings;
 	}
 
 	/**
@@ -1690,6 +2650,67 @@ final class WP_Customize_Manager {
 		return $preview_url;
 	}
 
+	/**
+	 * Determines whether the admin and the frontend are on different domains.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 *
+	 * @return bool Whether cross-domain.
+	 */
+	public function is_cross_domain() {
+		$admin_origin = wp_parse_url( admin_url() );
+		$home_origin = wp_parse_url( home_url() );
+		$cross_domain = ( strtolower( $admin_origin['host'] ) !== strtolower( $home_origin['host'] ) );
+		return $cross_domain;
+	}
+
+	/**
+	 * Get URLs allowed to be previewed.
+	 *
+	 * If the front end and the admin are served from the same domain, load the
+	 * preview over ssl if the Customizer is being loaded over ssl. This avoids
+	 * insecure content warnings. This is not attempted if the admin and front end
+	 * are on different domains to avoid the case where the front end doesn't have
+	 * ssl certs. Domain mapping plugins can allow other urls in these conditions
+	 * using the customize_allowed_urls filter.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 *
+	 * @returns array Allowed URLs.
+	 */
+	public function get_allowed_urls() {
+		$allowed_urls = array( home_url( '/' ) );
+
+		if ( is_ssl() && ! $this->is_cross_domain() ) {
+			$allowed_urls[] = home_url( '/', 'https' );
+		}
+
+		/**
+		 * Filters the list of URLs allowed to be clicked and followed in the Customizer preview.
+		 *
+		 * @since 3.4.0
+		 *
+		 * @param array $allowed_urls An array of allowed URLs.
+		 */
+		$allowed_urls = array_unique( apply_filters( 'customize_allowed_urls', $allowed_urls ) );
+
+		return $allowed_urls;
+	}
+
+	/**
+	 * Get messenger channel.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 *
+	 * @return string Messenger channel.
+	 */
+	public function get_messenger_channel() {
+		return $this->messenger_channel;
+	}
+
 	/**
 	 * Set URL to link the user to when closing the Customizer.
 	 *
@@ -1799,40 +2820,33 @@ final class WP_Customize_Manager {
 	 * @since 4.4.0
 	 */
 	public function customize_pane_settings() {
-		/*
-		 * If the front end and the admin are served from the same domain, load the
-		 * preview over ssl if the Customizer is being loaded over ssl. This avoids
-		 * insecure content warnings. This is not attempted if the admin and front end
-		 * are on different domains to avoid the case where the front end doesn't have
-		 * ssl certs. Domain mapping plugins can allow other urls in these conditions
-		 * using the customize_allowed_urls filter.
-		 */
-
-		$allowed_urls = array( home_url( '/' ) );
-		$admin_origin = parse_url( admin_url() );
-		$home_origin  = parse_url( home_url() );
-		$cross_domain = ( strtolower( $admin_origin['host'] ) !== strtolower( $home_origin['host'] ) );
-
-		if ( is_ssl() && ! $cross_domain ) {
-			$allowed_urls[] = home_url( '/', 'https' );
-		}
-
-		/**
-		 * Filters the list of URLs allowed to be clicked and followed in the Customizer preview.
-		 *
-		 * @since 3.4.0
-		 *
-		 * @param array $allowed_urls An array of allowed URLs.
-		 */
-		$allowed_urls = array_unique( apply_filters( 'customize_allowed_urls', $allowed_urls ) );
 
 		$login_url = add_query_arg( array(
 			'interim-login' => 1,
 			'customize-login' => 1,
 		), wp_login_url() );
 
+		// Ensure dirty flags are set for modified settings.
+		foreach ( array_keys( $this->unsanitized_post_values() ) as $setting_id ) {
+			$setting = $this->get_setting( $setting_id );
+			if ( $setting ) {
+				$setting->dirty = true;
+			}
+		}
+
 		// Prepare Customizer settings to pass to JavaScript.
 		$settings = array(
+			'changeset' => array(
+				'uuid' => $this->changeset_uuid(),
+				'status' => $this->changeset_post_id() ? get_post_status( $this->changeset_post_id() ) : '',
+			),
+			'timeouts' => array(
+				'windowRefresh' => 250,
+				'changesetAutoSave' => AUTOSAVE_INTERVAL * 1000,
+				'keepAliveCheck' => 2500,
+				'reflowPaneContents' => 100,
+				'previewFrameSensitivity' => 2000,
+			),
 			'theme'    => array(
 				'stylesheet' => $this->get_stylesheet(),
 				'active'     => $this->is_theme_active(),
@@ -1842,8 +2856,8 @@ final class WP_Customize_Manager {
 				'parent'        => esc_url_raw( admin_url() ),
 				'activated'     => esc_url_raw( home_url( '/' ) ),
 				'ajax'          => esc_url_raw( admin_url( 'admin-ajax.php', 'relative' ) ),
-				'allowed'       => array_map( 'esc_url_raw', $allowed_urls ),
-				'isCrossDomain' => $cross_domain,
+				'allowed'       => array_map( 'esc_url_raw', $this->get_allowed_urls() ),
+				'isCrossDomain' => $this->is_cross_domain(),
 				'home'          => esc_url_raw( home_url( '/' ) ),
 				'login'         => esc_url_raw( $login_url ),
 			),
@@ -2337,7 +3351,8 @@ final class WP_Customize_Manager {
 	 * @see add_dynamic_settings()
 	 */
 	public function register_dynamic_settings() {
-		$this->add_dynamic_settings( array_keys( $this->unsanitized_post_values() ) );
+		$setting_ids = array_keys( $this->unsanitized_post_values() );
+		$this->add_dynamic_settings( $setting_ids );
 	}
 
 	/**
diff --git a/wp-includes/class-wp-customize-nav-menus.php b/wp-includes/class-wp-customize-nav-menus.php
index a4e494d5b3..2d9c13a40e 100644
--- a/wp-includes/class-wp-customize-nav-menus.php
+++ b/wp-includes/class-wp-customize-nav-menus.php
@@ -48,7 +48,12 @@ final class WP_Customize_Nav_Menus {
 		$this->previewed_menus = array();
 		$this->manager         = $manager;
 
-		// Skip useless hooks when the user can't manage nav menus anyway.
+		// See https://github.com/xwp/wp-customize-snapshots/blob/962586659688a5b1fd9ae93618b7ce2d4e7a421c/php/class-customize-snapshot-manager.php#L469-L499
+		add_action( 'customize_register', array( $this, 'customize_register' ), 11 );
+		add_filter( 'customize_dynamic_setting_args', array( $this, 'filter_dynamic_setting_args' ), 10, 2 );
+		add_filter( 'customize_dynamic_setting_class', array( $this, 'filter_dynamic_setting_class' ), 10, 3 );
+
+		// Skip remaining hooks when the user can't manage nav menus anyway.
 		if ( ! current_user_can( 'edit_theme_options' ) ) {
 			return;
 		}
@@ -58,9 +63,6 @@ final class WP_Customize_Nav_Menus {
 		add_action( 'wp_ajax_search-available-menu-items-customizer', array( $this, 'ajax_search_available_items' ) );
 		add_action( 'wp_ajax_customize-nav-menus-insert-auto-draft', array( $this, 'ajax_insert_auto_draft_post' ) );
 		add_action( 'customize_controls_enqueue_scripts', array( $this, 'enqueue_scripts' ) );
-		add_action( 'customize_register', array( $this, 'customize_register' ), 11 );
-		add_filter( 'customize_dynamic_setting_args', array( $this, 'filter_dynamic_setting_args' ), 10, 2 );
-		add_filter( 'customize_dynamic_setting_class', array( $this, 'filter_dynamic_setting_class' ), 10, 3 );
 		add_action( 'customize_controls_print_footer_scripts', array( $this, 'print_templates' ) );
 		add_action( 'customize_controls_print_footer_scripts', array( $this, 'available_items_template' ) );
 		add_action( 'customize_preview_init', array( $this, 'customize_preview_init' ) );
@@ -486,6 +488,23 @@ final class WP_Customize_Nav_Menus {
 	 */
 	public function customize_register() {
 
+		/*
+		 * Preview settings for nav menus early so that the sections and controls will be added properly.
+		 * See https://github.com/xwp/wp-customize-snapshots/blob/962586659688a5b1fd9ae93618b7ce2d4e7a421c/php/class-customize-snapshot-manager.php#L506-L543
+		 */
+		$nav_menus_setting_ids = array();
+		foreach ( array_keys( $this->manager->unsanitized_post_values() ) as $setting_id ) {
+			if ( preg_match( '/^(nav_menu_locations|nav_menu|nav_menu_item)\[/', $setting_id ) ) {
+				$nav_menus_setting_ids[] = $setting_id;
+			}
+		}
+		foreach ( $nav_menus_setting_ids as $setting_id ) {
+			$setting = $this->manager->get_setting( $setting_id );
+			if ( $setting ) {
+				$setting->preview();
+			}
+		}
+
 		// Require JS-rendered control types.
 		$this->manager->register_panel_type( 'WP_Customize_Nav_Menus_Panel' );
 		$this->manager->register_control_type( 'WP_Customize_Nav_Menu_Control' );
diff --git a/wp-includes/class-wp-customize-widgets.php b/wp-includes/class-wp-customize-widgets.php
index 973fa137e6..74031194fd 100644
--- a/wp-includes/class-wp-customize-widgets.php
+++ b/wp-includes/class-wp-customize-widgets.php
@@ -93,16 +93,18 @@ final class WP_Customize_Widgets {
 	public function __construct( $manager ) {
 		$this->manager = $manager;
 
-		// Skip useless hooks when the user can't manage widgets anyway.
+		// See https://github.com/xwp/wp-customize-snapshots/blob/962586659688a5b1fd9ae93618b7ce2d4e7a421c/php/class-customize-snapshot-manager.php#L420-L449
+		add_filter( 'customize_dynamic_setting_args',          array( $this, 'filter_customize_dynamic_setting_args' ), 10, 2 );
+		add_action( 'widgets_init',                            array( $this, 'register_settings' ), 95 );
+		add_action( 'customize_register',                      array( $this, 'schedule_customize_register' ), 1 );
+
+		// Skip remaining hooks when the user can't manage widgets anyway.
 		if ( ! current_user_can( 'edit_theme_options' ) ) {
 			return;
 		}
 
-		add_filter( 'customize_dynamic_setting_args',          array( $this, 'filter_customize_dynamic_setting_args' ), 10, 2 );
-		add_action( 'widgets_init',                            array( $this, 'register_settings' ), 95 );
 		add_action( 'wp_loaded',                               array( $this, 'override_sidebars_widgets_for_theme_switch' ) );
 		add_action( 'customize_controls_init',                 array( $this, 'customize_controls_init' ) );
-		add_action( 'customize_register',                      array( $this, 'schedule_customize_register' ), 1 );
 		add_action( 'customize_controls_enqueue_scripts',      array( $this, 'enqueue_scripts' ) );
 		add_action( 'customize_controls_print_styles',         array( $this, 'print_styles' ) );
 		add_action( 'customize_controls_print_scripts',        array( $this, 'print_scripts' ) );
@@ -276,6 +278,7 @@ final class WP_Customize_Widgets {
 
 		$this->old_sidebars_widgets = wp_get_sidebars_widgets();
 		add_filter( 'customize_value_old_sidebars_widgets_data', array( $this, 'filter_customize_value_old_sidebars_widgets_data' ) );
+		$this->manager->set_post_value( 'old_sidebars_widgets_data', $this->old_sidebars_widgets ); // Override any value cached in changeset.
 
 		// retrieve_widgets() looks at the global $sidebars_widgets
 		$sidebars_widgets = $this->old_sidebars_widgets;
diff --git a/wp-includes/customize/class-wp-customize-selective-refresh.php b/wp-includes/customize/class-wp-customize-selective-refresh.php
index 95c1934d38..6864eba63d 100644
--- a/wp-includes/customize/class-wp-customize-selective-refresh.php
+++ b/wp-includes/customize/class-wp-customize-selective-refresh.php
@@ -307,8 +307,6 @@ final class WP_Customize_Selective_Refresh {
 			return;
 		}
 
-		$this->manager->remove_preview_signature();
-
 		/*
 		 * Note that is_customize_preview() returning true will entail that the
 		 * user passed the 'customize' capability check and the nonce check, since
diff --git a/wp-includes/customize/class-wp-customize-theme-control.php b/wp-includes/customize/class-wp-customize-theme-control.php
index e696687298..fdd8f131da 100644
--- a/wp-includes/customize/class-wp-customize-theme-control.php
+++ b/wp-includes/customize/class-wp-customize-theme-control.php
@@ -63,8 +63,8 @@ class WP_Customize_Theme_Control extends WP_Customize_Control {
 	 */
 	public function content_template() {
 		$current_url = set_url_scheme( 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'] );
-		$active_url  = esc_url( remove_query_arg( 'theme', $current_url ) );
-		$preview_url = esc_url( add_query_arg( 'theme', '__THEME__', $current_url ) ); // Token because esc_url() strips curly braces.
+		$active_url  = esc_url( remove_query_arg( 'customize_theme', $current_url ) );
+		$preview_url = esc_url( add_query_arg( 'customize_theme', '__THEME__', $current_url ) ); // Token because esc_url() strips curly braces.
 		$preview_url = str_replace( '__THEME__', '{{ data.theme.id }}', $preview_url );
 		?>
 		<# if ( data.theme.isActiveTheme ) { #>
diff --git a/wp-includes/default-filters.php b/wp-includes/default-filters.php
index dba691ab66..6301f732c9 100644
--- a/wp-includes/default-filters.php
+++ b/wp-includes/default-filters.php
@@ -75,6 +75,7 @@ foreach ( array( 'user_url', 'link_url', 'link_image', 'link_rss', 'comment_url'
 
 // Slugs
 add_filter( 'pre_term_slug', 'sanitize_title' );
+add_filter( 'wp_insert_post_data', '_wp_customize_changeset_filter_insert_post_data', 10, 2 );
 
 // Keys
 foreach ( array( 'pre_post_type', 'pre_post_status', 'pre_post_comment_status', 'pre_post_ping_status' ) as $filter ) {
@@ -382,6 +383,7 @@ add_action( 'parse_request', 'rest_api_loaded' );
 add_action( 'wp_loaded', '_custom_header_background_just_in_time' );
 add_action( 'wp_head', '_custom_logo_header_styles' );
 add_action( 'plugins_loaded', '_wp_customize_include' );
+add_action( 'transition_post_status', '_wp_customize_publish_changeset', 10, 3 );
 add_action( 'admin_enqueue_scripts', '_wp_customize_loader_settings' );
 add_action( 'delete_attachment', '_delete_attachment_theme_mod' );
 
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 989772e765..40d4a300e1 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -5523,3 +5523,20 @@ function wp_raise_memory_limit( $context = 'admin' ) {
 
 	return false;
 }
+
+/**
+ * Generate a random UUID (version 4).
+ *
+ * @since 4.7.0
+ *
+ * @return string UUID.
+ */
+function wp_generate_uuid4() {
+	return sprintf( '%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
+		mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ),
+		mt_rand( 0, 0xffff ),
+		mt_rand( 0, 0x0fff ) | 0x4000,
+		mt_rand( 0, 0x3fff ) | 0x8000,
+		mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff ), mt_rand( 0, 0xffff )
+	);
+}
diff --git a/wp-includes/functions.wp-scripts.php b/wp-includes/functions.wp-scripts.php
index cec5ca9d65..dccaaf262a 100644
--- a/wp-includes/functions.wp-scripts.php
+++ b/wp-includes/functions.wp-scripts.php
@@ -34,7 +34,7 @@ function wp_scripts() {
  * @param string $function Function name.
  */
 function _wp_scripts_maybe_doing_it_wrong( $function ) {
-	if ( did_action( 'init' ) ) {
+	if ( did_action( 'init' ) || did_action( 'admin_enqueue_scripts' ) || did_action( 'wp_enqueue_scripts' ) || did_action( 'login_enqueue_scripts' ) ) {
 		return;
 	}
 
diff --git a/wp-includes/js/customize-base.js b/wp-includes/js/customize-base.js
index 20bb74a199..11b868c85e 100644
--- a/wp-includes/js/customize-base.js
+++ b/wp-includes/js/customize-base.js
@@ -637,22 +637,24 @@ window.wp = window.wp || {};
 		/**
 		 * Initialize Messenger.
 		 *
-		 * @param  {object} params        Parameters to configure the messenger.
-		 *         {string} .url          The URL to communicate with.
-		 *         {window} .targetWindow The window instance to communicate with. Default window.parent.
-		 *         {string} .channel      If provided, will send the channel with each message and only accept messages a matching channel.
-		 * @param  {object} options       Extend any instance parameter or method with this object.
+		 * @param  {object} params - Parameters to configure the messenger.
+		 *         {string} params.url - The URL to communicate with.
+		 *         {window} params.targetWindow - The window instance to communicate with. Default window.parent.
+		 *         {string} params.channel - If provided, will send the channel with each message and only accept messages a matching channel.
+		 * @param  {object} options - Extend any instance parameter or method with this object.
 		 */
 		initialize: function( params, options ) {
 			// Target the parent frame by default, but only if a parent frame exists.
-			var defaultTarget = window.parent == window ? null : window.parent;
+			var defaultTarget = window.parent === window ? null : window.parent;
 
 			$.extend( this, options || {} );
 
 			this.add( 'channel', params.channel );
 			this.add( 'url', params.url || '' );
 			this.add( 'origin', this.url() ).link( this.url ).setter( function( to ) {
-				return to.replace( /([^:]+:\/\/[^\/]+).*/, '$1' );
+				var urlParser = document.createElement( 'a' );
+				urlParser.href = to;
+				return urlParser.protocol + '//' + urlParser.hostname;
 			});
 
 			// first add with no value
@@ -807,6 +809,40 @@ window.wp = window.wp || {};
 		return result;
 	};
 
+	/**
+	 * Utility function namespace
+	 */
+	api.utils = {};
+
+	/**
+	 * Parse query string.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 *
+	 * @param {string} queryString Query string.
+	 * @returns {object} Parsed query string.
+	 */
+	api.utils.parseQueryString = function parseQueryString( queryString ) {
+		var queryParams = {};
+		_.each( queryString.split( '&' ), function( pair ) {
+			var parts, key, value;
+			parts = pair.split( '=', 2 );
+			if ( ! parts[0] ) {
+				return;
+			}
+			key = decodeURIComponent( parts[0].replace( /\+/g, ' ' ) );
+			key = key.replace( / /g, '_' ); // What PHP does.
+			if ( _.isUndefined( parts[1] ) ) {
+				value = null;
+			} else {
+				value = decodeURIComponent( parts[1].replace( /\+/g, ' ' ) );
+			}
+			queryParams[ key ] = value;
+		} );
+		return queryParams;
+	};
+
 	// Expose the API publicly on window.wp.customize
 	exports.customize = api;
 })( wp, jQuery );
diff --git a/wp-includes/js/customize-base.min.js b/wp-includes/js/customize-base.min.js
index 0581b8f253..de39288ef0 100644
--- a/wp-includes/js/customize-base.min.js
+++ b/wp-includes/js/customize-base.min.js
@@ -1 +1 @@
-window.wp=window.wp||{},function(a,b){var c,d,e={},f=Array.prototype.slice;c=function(){},d=function(a,d,e){var f;return f=d&&d.hasOwnProperty("constructor")?d.constructor:function(){var b=a.apply(this,arguments);return b},b.extend(f,a),c.prototype=a.prototype,f.prototype=new c,d&&b.extend(f.prototype,d),e&&b.extend(f,e),f.prototype.constructor=f,f.__super__=a.prototype,f},e.Class=function(a,c,d){var f,g=arguments;return a&&c&&e.Class.applicator===a&&(g=c,b.extend(this,d||{})),f=this,this.instance&&(f=function(){return f.instance.apply(f,arguments)},b.extend(f,this)),f.initialize.apply(f,g),f},e.Class.extend=function(a,b){var c=d(this,a,b);return c.extend=this.extend,c},e.Class.applicator={},e.Class.prototype.initialize=function(){},e.Class.prototype.extended=function(a){for(var b=this;"undefined"!=typeof b.constructor;){if(b.constructor===a)return!0;if("undefined"==typeof b.constructor.__super__)return!1;b=b.constructor.__super__}return!1},e.Events={trigger:function(a){return this.topics&&this.topics[a]&&this.topics[a].fireWith(this,f.call(arguments,1)),this},bind:function(a){return this.topics=this.topics||{},this.topics[a]=this.topics[a]||b.Callbacks(),this.topics[a].add.apply(this.topics[a],f.call(arguments,1)),this},unbind:function(a){return this.topics&&this.topics[a]&&this.topics[a].remove.apply(this.topics[a],f.call(arguments,1)),this}},e.Value=e.Class.extend({initialize:function(a,c){this._value=a,this.callbacks=b.Callbacks(),this._dirty=!1,b.extend(this,c||{}),this.set=b.proxy(this.set,this)},instance:function(){return arguments.length?this.set.apply(this,arguments):this.get()},get:function(){return this._value},set:function(a){var b=this._value;return a=this._setter.apply(this,arguments),a=this.validate(a),null===a||_.isEqual(b,a)?this:(this._value=a,this._dirty=!0,this.callbacks.fireWith(this,[a,b]),this)},_setter:function(a){return a},setter:function(a){var b=this.get();return this._setter=a,this._value=null,this.set(b),this},resetSetter:function(){return this._setter=this.constructor.prototype._setter,this.set(this.get()),this},validate:function(a){return a},bind:function(){return this.callbacks.add.apply(this.callbacks,arguments),this},unbind:function(){return this.callbacks.remove.apply(this.callbacks,arguments),this},link:function(){var a=this.set;return b.each(arguments,function(){this.bind(a)}),this},unlink:function(){var a=this.set;return b.each(arguments,function(){this.unbind(a)}),this},sync:function(){var a=this;return b.each(arguments,function(){a.link(this),this.link(a)}),this},unsync:function(){var a=this;return b.each(arguments,function(){a.unlink(this),this.unlink(a)}),this}}),e.Values=e.Class.extend({defaultConstructor:e.Value,initialize:function(a){b.extend(this,a||{}),this._value={},this._deferreds={}},instance:function(a){return 1===arguments.length?this.value(a):this.when.apply(this,arguments)},value:function(a){return this._value[a]},has:function(a){return"undefined"!=typeof this._value[a]},add:function(a,b){return this.has(a)?this.value(a):(this._value[a]=b,b.parent=this,b.extended(e.Value)&&b.bind(this._change),this.trigger("add",b),this._deferreds[a]&&this._deferreds[a].resolve(),this._value[a])},create:function(a){return this.add(a,new this.defaultConstructor(e.Class.applicator,f.call(arguments,1)))},each:function(a,c){c="undefined"==typeof c?this:c,b.each(this._value,function(b,d){a.call(c,d,b)})},remove:function(a){var b;this.has(a)&&(b=this.value(a),this.trigger("remove",b),b.extended(e.Value)&&b.unbind(this._change),delete b.parent),delete this._value[a],delete this._deferreds[a]},when:function(){var a=this,c=f.call(arguments),d=b.Deferred();return b.isFunction(c[c.length-1])&&d.done(c.pop()),b.when.apply(b,b.map(c,function(c){return a.has(c)?void 0:a._deferreds[c]=a._deferreds[c]||b.Deferred()})).done(function(){var e=b.map(c,function(b){return a(b)});return e.length!==c.length?void a.when.apply(a,c).done(function(){d.resolveWith(a,e)}):void d.resolveWith(a,e)}),d.promise()},_change:function(){this.parent.trigger("change",this)}}),b.extend(e.Values.prototype,e.Events),e.ensure=function(a){return"string"==typeof a?b(a):a},e.Element=e.Value.extend({initialize:function(a,c){var d,f,g,h=this,i=e.Element.synchronizer.html;this.element=e.ensure(a),this.events="",this.element.is("input, select, textarea")&&(this.events+="change",i=e.Element.synchronizer.val,this.element.is("input")?(d=this.element.prop("type"),e.Element.synchronizer[d]&&(i=e.Element.synchronizer[d]),"text"===d||"password"===d?this.events+=" keyup":"range"===d&&(this.events+=" input propertychange")):this.element.is("textarea")&&(this.events+=" keyup")),e.Value.prototype.initialize.call(this,null,b.extend(c||{},i)),this._value=this.get(),f=this.update,g=this.refresh,this.update=function(a){a!==g.call(h)&&f.apply(this,arguments)},this.refresh=function(){h.set(g.call(h))},this.bind(this.update),this.element.bind(this.events,this.refresh)},find:function(a){return b(a,this.element)},refresh:function(){},update:function(){}}),e.Element.synchronizer={},b.each(["html","val"],function(a,b){e.Element.synchronizer[b]={update:function(a){this.element[b](a)},refresh:function(){return this.element[b]()}}}),e.Element.synchronizer.checkbox={update:function(a){this.element.prop("checked",a)},refresh:function(){return this.element.prop("checked")}},e.Element.synchronizer.radio={update:function(a){this.element.filter(function(){return this.value===a}).prop("checked",!0)},refresh:function(){return this.element.filter(":checked").val()}},b.support.postMessage=!!window.postMessage,e.Messenger=e.Class.extend({add:function(a,b,c){return this[a]=new e.Value(b,c)},initialize:function(a,c){var d=window.parent==window?null:window.parent;b.extend(this,c||{}),this.add("channel",a.channel),this.add("url",a.url||""),this.add("origin",this.url()).link(this.url).setter(function(a){return a.replace(/([^:]+:\/\/[^\/]+).*/,"$1")}),this.add("targetWindow",null),this.targetWindow.set=function(a){var b=this._value;return a=this._setter.apply(this,arguments),a=this.validate(a),null===a||b===a?this:(this._value=a,this._dirty=!0,this.callbacks.fireWith(this,[a,b]),this)},this.targetWindow(a.targetWindow||d),this.receive=b.proxy(this.receive,this),this.receive.guid=b.guid++,b(window).on("message",this.receive)},destroy:function(){b(window).off("message",this.receive)},receive:function(a){var b;a=a.originalEvent,this.targetWindow&&this.targetWindow()&&(this.origin()&&a.origin!==this.origin()||"string"==typeof a.data&&"{"===a.data[0]&&(b=JSON.parse(a.data),b&&b.id&&"undefined"!=typeof b.data&&((b.channel||this.channel())&&this.channel()!==b.channel||this.trigger(b.id,b.data))))},send:function(a,b){var c;b="undefined"==typeof b?null:b,this.url()&&this.targetWindow()&&(c={id:a,data:b},this.channel()&&(c.channel=this.channel()),this.targetWindow().postMessage(JSON.stringify(c),this.origin()))}}),b.extend(e.Messenger.prototype,e.Events),e.Notification=e.Class.extend({initialize:function(a,b){var c;this.code=a,c=_.extend({message:null,type:"error",fromServer:!1,data:null,setting:null},b),delete c.code,_.extend(this,c)}}),e=b.extend(new e.Values,e),e.get=function(){var a={};return this.each(function(b,c){a[c]=b.get()}),a},a.customize=e}(wp,jQuery);
\ No newline at end of file
+window.wp=window.wp||{},function(a,b){var c,d,e={},f=Array.prototype.slice;c=function(){},d=function(a,d,e){var f;return f=d&&d.hasOwnProperty("constructor")?d.constructor:function(){var b=a.apply(this,arguments);return b},b.extend(f,a),c.prototype=a.prototype,f.prototype=new c,d&&b.extend(f.prototype,d),e&&b.extend(f,e),f.prototype.constructor=f,f.__super__=a.prototype,f},e.Class=function(a,c,d){var f,g=arguments;return a&&c&&e.Class.applicator===a&&(g=c,b.extend(this,d||{})),f=this,this.instance&&(f=function(){return f.instance.apply(f,arguments)},b.extend(f,this)),f.initialize.apply(f,g),f},e.Class.extend=function(a,b){var c=d(this,a,b);return c.extend=this.extend,c},e.Class.applicator={},e.Class.prototype.initialize=function(){},e.Class.prototype.extended=function(a){for(var b=this;"undefined"!=typeof b.constructor;){if(b.constructor===a)return!0;if("undefined"==typeof b.constructor.__super__)return!1;b=b.constructor.__super__}return!1},e.Events={trigger:function(a){return this.topics&&this.topics[a]&&this.topics[a].fireWith(this,f.call(arguments,1)),this},bind:function(a){return this.topics=this.topics||{},this.topics[a]=this.topics[a]||b.Callbacks(),this.topics[a].add.apply(this.topics[a],f.call(arguments,1)),this},unbind:function(a){return this.topics&&this.topics[a]&&this.topics[a].remove.apply(this.topics[a],f.call(arguments,1)),this}},e.Value=e.Class.extend({initialize:function(a,c){this._value=a,this.callbacks=b.Callbacks(),this._dirty=!1,b.extend(this,c||{}),this.set=b.proxy(this.set,this)},instance:function(){return arguments.length?this.set.apply(this,arguments):this.get()},get:function(){return this._value},set:function(a){var b=this._value;return a=this._setter.apply(this,arguments),a=this.validate(a),null===a||_.isEqual(b,a)?this:(this._value=a,this._dirty=!0,this.callbacks.fireWith(this,[a,b]),this)},_setter:function(a){return a},setter:function(a){var b=this.get();return this._setter=a,this._value=null,this.set(b),this},resetSetter:function(){return this._setter=this.constructor.prototype._setter,this.set(this.get()),this},validate:function(a){return a},bind:function(){return this.callbacks.add.apply(this.callbacks,arguments),this},unbind:function(){return this.callbacks.remove.apply(this.callbacks,arguments),this},link:function(){var a=this.set;return b.each(arguments,function(){this.bind(a)}),this},unlink:function(){var a=this.set;return b.each(arguments,function(){this.unbind(a)}),this},sync:function(){var a=this;return b.each(arguments,function(){a.link(this),this.link(a)}),this},unsync:function(){var a=this;return b.each(arguments,function(){a.unlink(this),this.unlink(a)}),this}}),e.Values=e.Class.extend({defaultConstructor:e.Value,initialize:function(a){b.extend(this,a||{}),this._value={},this._deferreds={}},instance:function(a){return 1===arguments.length?this.value(a):this.when.apply(this,arguments)},value:function(a){return this._value[a]},has:function(a){return"undefined"!=typeof this._value[a]},add:function(a,b){return this.has(a)?this.value(a):(this._value[a]=b,b.parent=this,b.extended(e.Value)&&b.bind(this._change),this.trigger("add",b),this._deferreds[a]&&this._deferreds[a].resolve(),this._value[a])},create:function(a){return this.add(a,new this.defaultConstructor(e.Class.applicator,f.call(arguments,1)))},each:function(a,c){c="undefined"==typeof c?this:c,b.each(this._value,function(b,d){a.call(c,d,b)})},remove:function(a){var b;this.has(a)&&(b=this.value(a),this.trigger("remove",b),b.extended(e.Value)&&b.unbind(this._change),delete b.parent),delete this._value[a],delete this._deferreds[a]},when:function(){var a=this,c=f.call(arguments),d=b.Deferred();return b.isFunction(c[c.length-1])&&d.done(c.pop()),b.when.apply(b,b.map(c,function(c){return a.has(c)?void 0:a._deferreds[c]=a._deferreds[c]||b.Deferred()})).done(function(){var e=b.map(c,function(b){return a(b)});return e.length!==c.length?void a.when.apply(a,c).done(function(){d.resolveWith(a,e)}):void d.resolveWith(a,e)}),d.promise()},_change:function(){this.parent.trigger("change",this)}}),b.extend(e.Values.prototype,e.Events),e.ensure=function(a){return"string"==typeof a?b(a):a},e.Element=e.Value.extend({initialize:function(a,c){var d,f,g,h=this,i=e.Element.synchronizer.html;this.element=e.ensure(a),this.events="",this.element.is("input, select, textarea")&&(this.events+="change",i=e.Element.synchronizer.val,this.element.is("input")?(d=this.element.prop("type"),e.Element.synchronizer[d]&&(i=e.Element.synchronizer[d]),"text"===d||"password"===d?this.events+=" keyup":"range"===d&&(this.events+=" input propertychange")):this.element.is("textarea")&&(this.events+=" keyup")),e.Value.prototype.initialize.call(this,null,b.extend(c||{},i)),this._value=this.get(),f=this.update,g=this.refresh,this.update=function(a){a!==g.call(h)&&f.apply(this,arguments)},this.refresh=function(){h.set(g.call(h))},this.bind(this.update),this.element.bind(this.events,this.refresh)},find:function(a){return b(a,this.element)},refresh:function(){},update:function(){}}),e.Element.synchronizer={},b.each(["html","val"],function(a,b){e.Element.synchronizer[b]={update:function(a){this.element[b](a)},refresh:function(){return this.element[b]()}}}),e.Element.synchronizer.checkbox={update:function(a){this.element.prop("checked",a)},refresh:function(){return this.element.prop("checked")}},e.Element.synchronizer.radio={update:function(a){this.element.filter(function(){return this.value===a}).prop("checked",!0)},refresh:function(){return this.element.filter(":checked").val()}},b.support.postMessage=!!window.postMessage,e.Messenger=e.Class.extend({add:function(a,b,c){return this[a]=new e.Value(b,c)},initialize:function(a,c){var d=window.parent===window?null:window.parent;b.extend(this,c||{}),this.add("channel",a.channel),this.add("url",a.url||""),this.add("origin",this.url()).link(this.url).setter(function(a){var b=document.createElement("a");return b.href=a,b.protocol+"//"+b.hostname}),this.add("targetWindow",null),this.targetWindow.set=function(a){var b=this._value;return a=this._setter.apply(this,arguments),a=this.validate(a),null===a||b===a?this:(this._value=a,this._dirty=!0,this.callbacks.fireWith(this,[a,b]),this)},this.targetWindow(a.targetWindow||d),this.receive=b.proxy(this.receive,this),this.receive.guid=b.guid++,b(window).on("message",this.receive)},destroy:function(){b(window).off("message",this.receive)},receive:function(a){var b;a=a.originalEvent,this.targetWindow&&this.targetWindow()&&(this.origin()&&a.origin!==this.origin()||"string"==typeof a.data&&"{"===a.data[0]&&(b=JSON.parse(a.data),b&&b.id&&"undefined"!=typeof b.data&&((b.channel||this.channel())&&this.channel()!==b.channel||this.trigger(b.id,b.data))))},send:function(a,b){var c;b="undefined"==typeof b?null:b,this.url()&&this.targetWindow()&&(c={id:a,data:b},this.channel()&&(c.channel=this.channel()),this.targetWindow().postMessage(JSON.stringify(c),this.origin()))}}),b.extend(e.Messenger.prototype,e.Events),e.Notification=e.Class.extend({initialize:function(a,b){var c;this.code=a,c=_.extend({message:null,type:"error",fromServer:!1,data:null,setting:null},b),delete c.code,_.extend(this,c)}}),e=b.extend(new e.Values,e),e.get=function(){var a={};return this.each(function(b,c){a[c]=b.get()}),a},e.utils={},e.utils.parseQueryString=function(a){var b={};return _.each(a.split("&"),function(a){var c,d,e;c=a.split("=",2),c[0]&&(d=decodeURIComponent(c[0].replace(/\+/g," ")),d=d.replace(/ /g,"_"),e=_.isUndefined(c[1])?null:decodeURIComponent(c[1].replace(/\+/g," ")),b[d]=e)}),b},a.customize=e}(wp,jQuery);
\ No newline at end of file
diff --git a/wp-includes/js/customize-loader.js b/wp-includes/js/customize-loader.js
index 85ad7455be..1990d1a24d 100644
--- a/wp-includes/js/customize-loader.js
+++ b/wp-includes/js/customize-loader.js
@@ -132,6 +132,19 @@ window.wp = window.wp || {};
 				targetWindow: this.iframe[0].contentWindow
 			});
 
+			// Expose the changeset UUID on the parent window's URL so that the customized state can survive a refresh.
+			if ( history.replaceState ) {
+				this.messenger.bind( 'changeset-uuid', function( changesetUuid ) {
+					var urlParser = document.createElement( 'a' );
+					urlParser.href = location.href;
+					urlParser.search = $.param( _.extend(
+						api.utils.parseQueryString( urlParser.search.substr( 1 ) ),
+						{ changeset_uuid: changesetUuid }
+					) );
+					history.replaceState( { customize: urlParser.href }, '', urlParser.href );
+				} );
+			}
+
 			// Wait for the connection from the iframe before sending any postMessage events.
 			this.messenger.bind( 'ready', function() {
 				Loader.messenger.send( 'back' );
diff --git a/wp-includes/js/customize-loader.min.js b/wp-includes/js/customize-loader.min.js
index 890cbe0203..25e8e7211a 100644
--- a/wp-includes/js/customize-loader.min.js
+++ b/wp-includes/js/customize-loader.min.js
@@ -1 +1 @@
-window.wp=window.wp||{},function(a,b){var c,d=wp.customize;b.extend(b.support,{history:!(!window.history||!history.pushState),hashchange:"onhashchange"in window&&(void 0===document.documentMode||document.documentMode>7)}),c=b.extend({},d.Events,{initialize:function(){this.body=b(document.body),c.settings&&b.support.postMessage&&(b.support.cors||!c.settings.isCrossDomain)&&(this.window=b(window),this.element=b('<div id="customize-container" />').appendTo(this.body),this.bind("open",this.overlay.show),this.bind("close",this.overlay.hide),b("#wpbody").on("click",".load-customize",function(a){a.preventDefault(),c.link=b(this),c.open(c.link.attr("href"))}),b.support.history&&this.window.on("popstate",c.popstate),b.support.hashchange&&(this.window.on("hashchange",c.hashchange),this.window.triggerHandler("hashchange")))},popstate:function(a){var b=a.originalEvent.state;b&&b.customize?c.open(b.customize):c.active&&c.close()},hashchange:function(){var a=window.location.toString().split("#")[1];a&&0===a.indexOf("wp_customize=on")&&c.open(c.settings.url+"?"+a),a||b.support.history||c.close()},beforeunload:function(){return c.saved()?void 0:c.settings.l10n.saveAlert},open:function(a){if(!this.active){if(c.settings.browser.mobile)return window.location=a;this.originalDocumentTitle=document.title,this.active=!0,this.body.addClass("customize-loading"),this.saved=new d.Value(!0),this.iframe=b("<iframe />",{src:a,title:c.settings.l10n.mainIframeTitle}).appendTo(this.element),this.iframe.one("load",this.loaded),this.messenger=new d.Messenger({url:a,channel:"loader",targetWindow:this.iframe[0].contentWindow}),this.messenger.bind("ready",function(){c.messenger.send("back")}),this.messenger.bind("close",function(){b.support.history?history.back():b.support.hashchange?window.location.hash="":c.close()}),b(window).on("beforeunload",this.beforeunload),this.messenger.bind("saved",function(){c.saved(!0)}),this.messenger.bind("change",function(){c.saved(!1)}),this.messenger.bind("title",function(a){window.document.title=a}),this.pushState(a),this.trigger("open")}},pushState:function(a){var c=a.split("?")[1];b.support.history&&window.location.href!==a?history.pushState({customize:a},"",a):!b.support.history&&b.support.hashchange&&c&&(window.location.hash="wp_customize=on&"+c),this.trigger("open")},opened:function(){c.body.addClass("customize-active full-overlay-active").attr("aria-busy","true")},close:function(){if(this.active){if(!this.saved()&&!confirm(c.settings.l10n.saveAlert))return void history.forward();this.active=!1,this.trigger("close"),this.originalDocumentTitle&&(document.title=this.originalDocumentTitle)}},closed:function(){c.iframe.remove(),c.messenger.destroy(),c.iframe=null,c.messenger=null,c.saved=null,c.body.removeClass("customize-active full-overlay-active").removeClass("customize-loading"),b(window).off("beforeunload",c.beforeunload),c.link&&c.link.focus()},loaded:function(){c.body.removeClass("customize-loading").attr("aria-busy","false")},overlay:{show:function(){this.element.fadeIn(200,c.opened)},hide:function(){this.element.fadeOut(200,c.closed)}}}),b(function(){c.settings=_wpCustomizeLoaderSettings,c.initialize()}),d.Loader=c}(wp,jQuery);
\ No newline at end of file
+window.wp=window.wp||{},function(a,b){var c,d=wp.customize;b.extend(b.support,{history:!(!window.history||!history.pushState),hashchange:"onhashchange"in window&&(void 0===document.documentMode||document.documentMode>7)}),c=b.extend({},d.Events,{initialize:function(){this.body=b(document.body),c.settings&&b.support.postMessage&&(b.support.cors||!c.settings.isCrossDomain)&&(this.window=b(window),this.element=b('<div id="customize-container" />').appendTo(this.body),this.bind("open",this.overlay.show),this.bind("close",this.overlay.hide),b("#wpbody").on("click",".load-customize",function(a){a.preventDefault(),c.link=b(this),c.open(c.link.attr("href"))}),b.support.history&&this.window.on("popstate",c.popstate),b.support.hashchange&&(this.window.on("hashchange",c.hashchange),this.window.triggerHandler("hashchange")))},popstate:function(a){var b=a.originalEvent.state;b&&b.customize?c.open(b.customize):c.active&&c.close()},hashchange:function(){var a=window.location.toString().split("#")[1];a&&0===a.indexOf("wp_customize=on")&&c.open(c.settings.url+"?"+a),a||b.support.history||c.close()},beforeunload:function(){return c.saved()?void 0:c.settings.l10n.saveAlert},open:function(a){if(!this.active){if(c.settings.browser.mobile)return window.location=a;this.originalDocumentTitle=document.title,this.active=!0,this.body.addClass("customize-loading"),this.saved=new d.Value(!0),this.iframe=b("<iframe />",{src:a,title:c.settings.l10n.mainIframeTitle}).appendTo(this.element),this.iframe.one("load",this.loaded),this.messenger=new d.Messenger({url:a,channel:"loader",targetWindow:this.iframe[0].contentWindow}),history.replaceState&&this.messenger.bind("changeset-uuid",function(a){var c=document.createElement("a");c.href=location.href,c.search=b.param(_.extend(d.utils.parseQueryString(c.search.substr(1)),{changeset_uuid:a})),history.replaceState({customize:c.href},"",c.href)}),this.messenger.bind("ready",function(){c.messenger.send("back")}),this.messenger.bind("close",function(){b.support.history?history.back():b.support.hashchange?window.location.hash="":c.close()}),b(window).on("beforeunload",this.beforeunload),this.messenger.bind("saved",function(){c.saved(!0)}),this.messenger.bind("change",function(){c.saved(!1)}),this.messenger.bind("title",function(a){window.document.title=a}),this.pushState(a),this.trigger("open")}},pushState:function(a){var c=a.split("?")[1];b.support.history&&window.location.href!==a?history.pushState({customize:a},"",a):!b.support.history&&b.support.hashchange&&c&&(window.location.hash="wp_customize=on&"+c),this.trigger("open")},opened:function(){c.body.addClass("customize-active full-overlay-active").attr("aria-busy","true")},close:function(){if(this.active){if(!this.saved()&&!confirm(c.settings.l10n.saveAlert))return void history.forward();this.active=!1,this.trigger("close"),this.originalDocumentTitle&&(document.title=this.originalDocumentTitle)}},closed:function(){c.iframe.remove(),c.messenger.destroy(),c.iframe=null,c.messenger=null,c.saved=null,c.body.removeClass("customize-active full-overlay-active").removeClass("customize-loading"),b(window).off("beforeunload",c.beforeunload),c.link&&c.link.focus()},loaded:function(){c.body.removeClass("customize-loading").attr("aria-busy","false")},overlay:{show:function(){this.element.fadeIn(200,c.opened)},hide:function(){this.element.fadeOut(200,c.closed)}}}),b(function(){c.settings=_wpCustomizeLoaderSettings,c.initialize()}),d.Loader=c}(wp,jQuery);
\ No newline at end of file
diff --git a/wp-includes/js/customize-preview-nav-menus.js b/wp-includes/js/customize-preview-nav-menus.js
index bd42f5e081..6b241cd72d 100644
--- a/wp-includes/js/customize-preview-nav-menus.js
+++ b/wp-includes/js/customize-preview-nav-menus.js
@@ -106,7 +106,7 @@ wp.customize.navMenusPreview = wp.customize.MenusCustomizerPreview = ( function(
 			 * @returns {boolean}
 			 */
 			isRelatedSetting: function( setting, newValue, oldValue ) {
-				var partial = this, navMenuLocationSetting, navMenuId, isNavMenuItemSetting;
+				var partial = this, navMenuLocationSetting, navMenuId, isNavMenuItemSetting, _newValue, _oldValue, urlParser;
 				if ( _.isString( setting ) ) {
 					setting = api( setting );
 				}
@@ -123,9 +123,23 @@ wp.customize.navMenusPreview = wp.customize.MenusCustomizerPreview = ( function(
 				 */
 				isNavMenuItemSetting = /^nav_menu_item\[/.test( setting.id );
 				if ( isNavMenuItemSetting && _.isObject( newValue ) && _.isObject( oldValue ) ) {
-					delete newValue.type_label;
-					delete oldValue.type_label;
-					if ( _.isEqual( oldValue, newValue ) ) {
+					_newValue = _.clone( newValue );
+					_oldValue = _.clone( oldValue );
+					delete _newValue.type_label;
+					delete _oldValue.type_label;
+
+					// Normalize URL scheme when parent frame is HTTPS to prevent selective refresh upon initial page load.
+					if ( 'https' === api.preview.scheme.get() ) {
+						urlParser = document.createElement( 'a' );
+						urlParser.href = _newValue.url;
+						urlParser.protocol = 'https:';
+						_newValue.url = urlParser.href;
+						urlParser.href = _oldValue.url;
+						urlParser.protocol = 'https:';
+						_oldValue.url = urlParser.href;
+					}
+
+					if ( _.isEqual( _oldValue, _newValue ) ) {
 						return false;
 					}
 				}
@@ -365,6 +379,11 @@ wp.customize.navMenusPreview = wp.customize.MenusCustomizerPreview = ( function(
 	self.highlightControls = function() {
 		var selector = '.menu-item';
 
+		// Skip adding highlights if not in the customizer preview iframe.
+		if ( ! api.settings.channel ) {
+			return;
+		}
+
 		// Focus on the menu item control when shift+clicking the menu item.
 		$( document ).on( 'click', selector, function( e ) {
 			var navMenuItemParts;
diff --git a/wp-includes/js/customize-preview-nav-menus.min.js b/wp-includes/js/customize-preview-nav-menus.min.js
index 4a7b05e4c8..36a73c7964 100644
--- a/wp-includes/js/customize-preview-nav-menus.min.js
+++ b/wp-includes/js/customize-preview-nav-menus.min.js
@@ -1 +1 @@
-wp.customize.navMenusPreview=wp.customize.MenusCustomizerPreview=function(a,b,c,d){"use strict";var e={data:{navMenuInstanceArgs:{}}};return"undefined"!=typeof _wpCustomizePreviewNavMenusExports&&b.extend(e.data,_wpCustomizePreviewNavMenusExports),e.init=function(){var a=this;d.selectiveRefresh&&(d.each(function(b){a.bindSettingListener(b)}),d.bind("add",function(b){a.bindSettingListener(b,{fire:!0})}),d.bind("remove",function(b){a.unbindSettingListener(b)}),d.selectiveRefresh.bind("render-partials-response",function(c){c.nav_menu_instance_args&&b.extend(a.data.navMenuInstanceArgs,c.nav_menu_instance_args)})),d.preview.bind("active",function(){a.highlightControls()})},d.selectiveRefresh&&(e.NavMenuInstancePartial=d.selectiveRefresh.Partial.extend({initialize:function(a,c){var e,f,g=this;if(e=a.match(/^nav_menu_instance\[([0-9a-f]{32})]$/),!e)throw new Error("Illegal id for nav_menu_instance partial. The key corresponds with the args HMAC.");if(f=e[1],c=c||{},c.params=b.extend({selector:'[data-customize-partial-id="'+a+'"]',navMenuArgs:c.constructingContainerContext||{},containerInclusive:!0},c.params||{}),d.selectiveRefresh.Partial.prototype.initialize.call(g,a,c),!b.isObject(g.params.navMenuArgs))throw new Error("Missing navMenuArgs");if(g.params.navMenuArgs.args_hmac!==f)throw new Error("args_hmac mismatch with id")},isRelatedSetting:function(a,c,e){var f,g,h,i=this;if(b.isString(a)&&(a=d(a)),h=/^nav_menu_item\[/.test(a.id),h&&b.isObject(c)&&b.isObject(e)&&(delete c.type_label,delete e.type_label,b.isEqual(e,c)))return!1;if(i.params.navMenuArgs.theme_location){if("nav_menu_locations["+i.params.navMenuArgs.theme_location+"]"===a.id)return!0;f=d("nav_menu_locations["+i.params.navMenuArgs.theme_location+"]")}return g=i.params.navMenuArgs.menu,!g&&f&&(g=f()),g?"nav_menu["+g+"]"===a.id||h&&(c&&c.nav_menu_term_id===g||e&&e.nav_menu_term_id===g):!1},refresh:function(){var c,e=this,f=a.Deferred();return b.isNumber(e.params.navMenuArgs.menu)?c=e.params.navMenuArgs.menu:e.params.navMenuArgs.theme_location&&d.has("nav_menu_locations["+e.params.navMenuArgs.theme_location+"]")&&(c=d("nav_menu_locations["+e.params.navMenuArgs.theme_location+"]").get()),c?d.selectiveRefresh.Partial.prototype.refresh.call(e):(e.fallback(),f.reject(),f.promise())},renderContent:function(b){var c=this,e=b.container;""===b.addedContent&&b.partial.fallback(),d.selectiveRefresh.Partial.prototype.renderContent.call(c,b)&&a(document).trigger("customize-preview-menu-refreshed",[{instanceNumber:null,wpNavArgs:b.context,wpNavMenuArgs:b.context,oldContainer:e,newContainer:b.container}])}}),d.selectiveRefresh.partialConstructor.nav_menu_instance=e.NavMenuInstancePartial,e.handleUnplacedNavMenuInstances=function(a){var c;return c=b.filter(b.values(e.data.navMenuInstanceArgs),function(a){return!d.selectiveRefresh.partial.has("nav_menu_instance["+a.args_hmac+"]")}),b.findWhere(c,a)?(d.selectiveRefresh.requestFullRefresh(),!0):!1},e.bindSettingListener=function(a,b){var c;return b=b||{},(c=a.id.match(/^nav_menu\[(-?\d+)]$/))?(a._navMenuId=parseInt(c[1],10),a.bind(this.onChangeNavMenuSetting),b.fire&&this.onChangeNavMenuSetting.call(a,a(),!1),!0):(c=a.id.match(/^nav_menu_item\[(-?\d+)]$/))?(a._navMenuItemId=parseInt(c[1],10),a.bind(this.onChangeNavMenuItemSetting),b.fire&&this.onChangeNavMenuItemSetting.call(a,a(),!1),!0):(c=a.id.match(/^nav_menu_locations\[(.+?)]/),c?(a._navMenuThemeLocation=c[1],a.bind(this.onChangeNavMenuLocationsSetting),b.fire&&this.onChangeNavMenuLocationsSetting.call(a,a(),!1),!0):!1)},e.unbindSettingListener=function(a){a.unbind(this.onChangeNavMenuSetting),a.unbind(this.onChangeNavMenuItemSetting),a.unbind(this.onChangeNavMenuLocationsSetting)},e.onChangeNavMenuSetting=function(){var a=this;e.handleUnplacedNavMenuInstances({menu:a._navMenuId}),d.each(function(b){b._navMenuThemeLocation&&a._navMenuId===b()&&e.handleUnplacedNavMenuInstances({theme_location:b._navMenuThemeLocation})})},e.onChangeNavMenuItemSetting=function(a,b){var c,f=a||b;c=d("nav_menu["+String(f.nav_menu_term_id)+"]"),c&&e.onChangeNavMenuSetting.call(c)},e.onChangeNavMenuLocationsSetting=function(){var a,c=this;e.handleUnplacedNavMenuInstances({theme_location:c._navMenuThemeLocation}),a=!!b.findWhere(b.values(e.data.navMenuInstanceArgs),{theme_location:c._navMenuThemeLocation}),a||d.selectiveRefresh.requestFullRefresh()}),e.highlightControls=function(){var b=".menu-item";a(document).on("click",b,function(b){var c;b.shiftKey&&(c=a(this).attr("class").match(/(?:^|\s)menu-item-(\d+)(?:\s|$)/),c&&(b.preventDefault(),b.stopPropagation(),d.preview.send("focus-nav-menu-item-control",parseInt(c[1],10))))})},d.bind("preview-ready",function(){e.init()}),e}(jQuery,_,wp,wp.customize);
\ No newline at end of file
+wp.customize.navMenusPreview=wp.customize.MenusCustomizerPreview=function(a,b,c,d){"use strict";var e={data:{navMenuInstanceArgs:{}}};return"undefined"!=typeof _wpCustomizePreviewNavMenusExports&&b.extend(e.data,_wpCustomizePreviewNavMenusExports),e.init=function(){var a=this;d.selectiveRefresh&&(d.each(function(b){a.bindSettingListener(b)}),d.bind("add",function(b){a.bindSettingListener(b,{fire:!0})}),d.bind("remove",function(b){a.unbindSettingListener(b)}),d.selectiveRefresh.bind("render-partials-response",function(c){c.nav_menu_instance_args&&b.extend(a.data.navMenuInstanceArgs,c.nav_menu_instance_args)})),d.preview.bind("active",function(){a.highlightControls()})},d.selectiveRefresh&&(e.NavMenuInstancePartial=d.selectiveRefresh.Partial.extend({initialize:function(a,c){var e,f,g=this;if(e=a.match(/^nav_menu_instance\[([0-9a-f]{32})]$/),!e)throw new Error("Illegal id for nav_menu_instance partial. The key corresponds with the args HMAC.");if(f=e[1],c=c||{},c.params=b.extend({selector:'[data-customize-partial-id="'+a+'"]',navMenuArgs:c.constructingContainerContext||{},containerInclusive:!0},c.params||{}),d.selectiveRefresh.Partial.prototype.initialize.call(g,a,c),!b.isObject(g.params.navMenuArgs))throw new Error("Missing navMenuArgs");if(g.params.navMenuArgs.args_hmac!==f)throw new Error("args_hmac mismatch with id")},isRelatedSetting:function(a,c,e){var f,g,h,i,j,k,l=this;if(b.isString(a)&&(a=d(a)),h=/^nav_menu_item\[/.test(a.id),h&&b.isObject(c)&&b.isObject(e)&&(i=b.clone(c),j=b.clone(e),delete i.type_label,delete j.type_label,"https"===d.preview.scheme.get()&&(k=document.createElement("a"),k.href=i.url,k.protocol="https:",i.url=k.href,k.href=j.url,k.protocol="https:",j.url=k.href),b.isEqual(j,i)))return!1;if(l.params.navMenuArgs.theme_location){if("nav_menu_locations["+l.params.navMenuArgs.theme_location+"]"===a.id)return!0;f=d("nav_menu_locations["+l.params.navMenuArgs.theme_location+"]")}return g=l.params.navMenuArgs.menu,!g&&f&&(g=f()),g?"nav_menu["+g+"]"===a.id||h&&(c&&c.nav_menu_term_id===g||e&&e.nav_menu_term_id===g):!1},refresh:function(){var c,e=this,f=a.Deferred();return b.isNumber(e.params.navMenuArgs.menu)?c=e.params.navMenuArgs.menu:e.params.navMenuArgs.theme_location&&d.has("nav_menu_locations["+e.params.navMenuArgs.theme_location+"]")&&(c=d("nav_menu_locations["+e.params.navMenuArgs.theme_location+"]").get()),c?d.selectiveRefresh.Partial.prototype.refresh.call(e):(e.fallback(),f.reject(),f.promise())},renderContent:function(b){var c=this,e=b.container;""===b.addedContent&&b.partial.fallback(),d.selectiveRefresh.Partial.prototype.renderContent.call(c,b)&&a(document).trigger("customize-preview-menu-refreshed",[{instanceNumber:null,wpNavArgs:b.context,wpNavMenuArgs:b.context,oldContainer:e,newContainer:b.container}])}}),d.selectiveRefresh.partialConstructor.nav_menu_instance=e.NavMenuInstancePartial,e.handleUnplacedNavMenuInstances=function(a){var c;return c=b.filter(b.values(e.data.navMenuInstanceArgs),function(a){return!d.selectiveRefresh.partial.has("nav_menu_instance["+a.args_hmac+"]")}),b.findWhere(c,a)?(d.selectiveRefresh.requestFullRefresh(),!0):!1},e.bindSettingListener=function(a,b){var c;return b=b||{},(c=a.id.match(/^nav_menu\[(-?\d+)]$/))?(a._navMenuId=parseInt(c[1],10),a.bind(this.onChangeNavMenuSetting),b.fire&&this.onChangeNavMenuSetting.call(a,a(),!1),!0):(c=a.id.match(/^nav_menu_item\[(-?\d+)]$/))?(a._navMenuItemId=parseInt(c[1],10),a.bind(this.onChangeNavMenuItemSetting),b.fire&&this.onChangeNavMenuItemSetting.call(a,a(),!1),!0):(c=a.id.match(/^nav_menu_locations\[(.+?)]/),c?(a._navMenuThemeLocation=c[1],a.bind(this.onChangeNavMenuLocationsSetting),b.fire&&this.onChangeNavMenuLocationsSetting.call(a,a(),!1),!0):!1)},e.unbindSettingListener=function(a){a.unbind(this.onChangeNavMenuSetting),a.unbind(this.onChangeNavMenuItemSetting),a.unbind(this.onChangeNavMenuLocationsSetting)},e.onChangeNavMenuSetting=function(){var a=this;e.handleUnplacedNavMenuInstances({menu:a._navMenuId}),d.each(function(b){b._navMenuThemeLocation&&a._navMenuId===b()&&e.handleUnplacedNavMenuInstances({theme_location:b._navMenuThemeLocation})})},e.onChangeNavMenuItemSetting=function(a,b){var c,f=a||b;c=d("nav_menu["+String(f.nav_menu_term_id)+"]"),c&&e.onChangeNavMenuSetting.call(c)},e.onChangeNavMenuLocationsSetting=function(){var a,c=this;e.handleUnplacedNavMenuInstances({theme_location:c._navMenuThemeLocation}),a=!!b.findWhere(b.values(e.data.navMenuInstanceArgs),{theme_location:c._navMenuThemeLocation}),a||d.selectiveRefresh.requestFullRefresh()}),e.highlightControls=function(){var b=".menu-item";d.settings.channel&&a(document).on("click",b,function(b){var c;b.shiftKey&&(c=a(this).attr("class").match(/(?:^|\s)menu-item-(\d+)(?:\s|$)/),c&&(b.preventDefault(),b.stopPropagation(),d.preview.send("focus-nav-menu-item-control",parseInt(c[1],10))))})},d.bind("preview-ready",function(){e.init()}),e}(jQuery,_,wp,wp.customize);
\ No newline at end of file
diff --git a/wp-includes/js/customize-preview-widgets.js b/wp-includes/js/customize-preview-widgets.js
index 5adaf05373..967d56af8e 100644
--- a/wp-includes/js/customize-preview-widgets.js
+++ b/wp-includes/js/customize-preview-widgets.js
@@ -572,6 +572,11 @@ wp.customize.widgetsPreview = wp.customize.WidgetCustomizerPreview = (function(
 		var self = this,
 			selector = this.widgetSelectors.join( ',' );
 
+		// Skip adding highlights if not in the customizer preview iframe.
+		if ( ! api.settings.channel ) {
+			return;
+		}
+
 		$( selector ).attr( 'title', this.l10n.widgetTooltip );
 
 		$( document ).on( 'mouseenter', selector, function() {
diff --git a/wp-includes/js/customize-preview-widgets.min.js b/wp-includes/js/customize-preview-widgets.min.js
index 0c16d08b8c..92625fa4de 100644
--- a/wp-includes/js/customize-preview-widgets.min.js
+++ b/wp-includes/js/customize-preview-widgets.min.js
@@ -1 +1 @@
-wp.customize.widgetsPreview=wp.customize.WidgetCustomizerPreview=function(a,b,c,d){var e;return e={renderedSidebars:{},renderedWidgets:{},registeredSidebars:[],registeredWidgets:{},widgetSelectors:[],preview:null,l10n:{widgetTooltip:""},selectiveRefreshableWidgets:{}},e.init=function(){var a=this;a.preview=d.preview,b.isEmpty(a.selectiveRefreshableWidgets)||a.addPartials(),a.buildWidgetSelectors(),a.highlightControls(),a.preview.bind("highlight-widget",a.highlightWidget),d.preview.bind("active",function(){a.highlightControls()})},e.WidgetPartial=d.selectiveRefresh.Partial.extend({initialize:function(a,c){var f,g=this;if(f=a.match(/^widget\[(.+)]$/),!f)throw new Error("Illegal id for widget partial.");g.widgetId=f[1],g.widgetIdParts=e.parseWidgetId(g.widgetId),c=c||{},c.params=b.extend({settings:[e.getWidgetSettingId(g.widgetId)],containerInclusive:!0},c.params||{}),d.selectiveRefresh.Partial.prototype.initialize.call(g,a,c)},refresh:function(){var b,c=this;return e.selectiveRefreshableWidgets[c.widgetIdParts.idBase]?d.selectiveRefresh.Partial.prototype.refresh.call(c):(b=a.Deferred(),b.reject(),c.fallback(),b.promise())},renderContent:function(a){var b=this;d.selectiveRefresh.Partial.prototype.renderContent.call(b,a)&&(d.preview.send("widget-updated",b.widgetId),d.selectiveRefresh.trigger("widget-updated",b))}}),e.SidebarPartial=d.selectiveRefresh.Partial.extend({initialize:function(a,c){var e,f=this;if(e=a.match(/^sidebar\[(.+)]$/),!e)throw new Error("Illegal id for sidebar partial.");if(f.sidebarId=e[1],c=c||{},c.params=b.extend({settings:["sidebars_widgets["+f.sidebarId+"]"]},c.params||{}),d.selectiveRefresh.Partial.prototype.initialize.call(f,a,c),!f.params.sidebarArgs)throw new Error("The sidebarArgs param was not provided.");if(f.params.settings.length>1)throw new Error("Expected SidebarPartial to only have one associated setting")},ready:function(){var a=this;b.each(a.settings(),function(c){d(c).bind(b.bind(a.handleSettingChange,a))}),d.selectiveRefresh.bind("partial-content-rendered",function(c){var f=c.partial.extended(e.WidgetPartial)&&-1!==b.indexOf(a.getWidgetIds(),c.partial.widgetId);f&&d.selectiveRefresh.trigger("sidebar-updated",a)}),d.bind("change",function(c){var d,f;f=e.parseWidgetSettingId(c.id),f&&(d=f.idBase,f.number&&(d+="-"+String(f.number)),-1!==b.indexOf(a.getWidgetIds(),d)&&a.ensureWidgetPlacementContainers(d))})},findDynamicSidebarBoundaryNodes:function(){var a,c,d=this,e={};return a=/^(dynamic_sidebar_before|dynamic_sidebar_after):(.+):(\d+)$/,c=function(f){b.each(f,function(f){var g;if(8===f.nodeType){if(g=f.nodeValue.match(a),!g||g[2]!==d.sidebarId)return;b.isUndefined(e[g[3]])&&(e[g[3]]={before:null,after:null,instanceNumber:parseInt(g[3],10)}),"dynamic_sidebar_before"===g[1]?e[g[3]].before=f:e[g[3]].after=f}else 1===f.nodeType&&c(f.childNodes)})},c(document.body.childNodes),b.values(e)},placements:function(){var a=this;return b.map(a.findDynamicSidebarBoundaryNodes(),function(b){return new d.selectiveRefresh.Placement({partial:a,container:null,startNode:b.before,endNode:b.after,context:{instanceNumber:b.instanceNumber}})})},getWidgetIds:function(){var a,c,e=this;if(a=e.settings()[0],!a)throw new Error("Missing associated setting.");if(!d.has(a))throw new Error("Setting does not exist.");if(c=d(a).get(),!b.isArray(c))throw new Error("Expected setting to be array of widget IDs");return c.slice(0)},reflowWidgets:function(){var a,c,e,f=this,g=[];return c=f.getWidgetIds(),a=f.placements(),e={},b.each(c,function(a){var b=d.selectiveRefresh.partial("widget["+a+"]");b&&(e[a]=b)}),b.each(a,function(a){var c,f=[],h=!1,i=-1;b.each(e,function(d){b.each(d.placements(),function(b){a.context.instanceNumber===b.context.sidebar_instance_number&&(c=b.container.index(),f.push({partial:d,placement:b,position:c}),i>c&&(h=!0),i=c)})}),h&&(b.each(f,function(b){a.endNode.parentNode.insertBefore(b.placement.container[0],a.endNode),d.selectiveRefresh.trigger("partial-content-moved",b.placement)}),g.push(a))}),g.length>0&&d.selectiveRefresh.trigger("sidebar-updated",f),g},ensureWidgetPlacementContainers:function(c){var f,g=this,h=!1,i="widget["+c+"]";return f=d.selectiveRefresh.partial(i),f||(f=new e.WidgetPartial(i,{params:{}}),d.selectiveRefresh.partial.add(f.id,f)),b.each(g.placements(),function(d){var e,i;e=b.find(f.placements(),function(a){return a.context.sidebar_instance_number===d.context.instanceNumber}),e||(i=a(g.params.sidebarArgs.before_widget.replace(/%1\$s/g,c).replace(/%2\$s/g,"widget")+g.params.sidebarArgs.after_widget),i[0]&&(i.attr("data-customize-partial-id",f.id),i.attr("data-customize-partial-type","widget"),i.attr("data-customize-widget-id",c),i.data("customize-partial-placement-context",{sidebar_id:g.sidebarId,sidebar_instance_number:d.context.instanceNumber}),d.endNode.parentNode.insertBefore(i[0],d.endNode),h=!0))}),h&&g.reflowWidgets(),f},handleSettingChange:function(a,c){var e,f,g,h=this,i=[];return(e=c.length>0&&0===a.length||a.length>0&&0===c.length)?void h.fallback():(f=b.difference(c,a),b.each(f,function(a){var c=d.selectiveRefresh.partial("widget["+a+"]");c&&b.each(c.placements(),function(a){var b=a.context.sidebar_id===h.sidebarId||a.context.sidebar_args&&a.context.sidebar_args.id===h.sidebarId;b&&a.container.remove()})}),g=b.difference(a,c),b.each(g,function(a){var b=h.ensureWidgetPlacementContainers(a);i.push(b)}),b.each(i,function(a){a.refresh()}),void d.selectiveRefresh.trigger("sidebar-updated",h))},refresh:function(){var c=this,e=a.Deferred();return e.fail(function(){c.fallback()}),0===c.placements().length?e.reject():(b.each(c.reflowWidgets(),function(a){d.selectiveRefresh.trigger("partial-content-rendered",a)}),e.resolve()),e.promise()}}),d.selectiveRefresh.partialConstructor.sidebar=e.SidebarPartial,d.selectiveRefresh.partialConstructor.widget=e.WidgetPartial,e.addPartials=function(){b.each(e.registeredSidebars,function(a){var b,c="sidebar["+a.id+"]";b=d.selectiveRefresh.partial(c),b||(b=new e.SidebarPartial(c,{params:{sidebarArgs:a}}),d.selectiveRefresh.partial.add(b.id,b))})},e.buildWidgetSelectors=function(){var b=this;a.each(b.registeredSidebars,function(c,d){var e,f,g,h=[d.before_widget,d.before_title,d.after_title,d.after_widget].join("");e=a(h),f=e.prop("tagName")||"",g=e.prop("className")||"",g&&(g=g.replace(/\S*%[12]\$s\S*/g,""),g=g.replace(/^\s+|\s+$/g,""),g&&(f+="."+g.split(/\s+/).join(".")),b.widgetSelectors.push(f))})},e.highlightWidget=function(b){var c=a(document.body),d=a("#"+b);c.find(".widget-customizer-highlighted-widget").removeClass("widget-customizer-highlighted-widget"),d.addClass("widget-customizer-highlighted-widget"),setTimeout(function(){d.removeClass("widget-customizer-highlighted-widget")},500)},e.highlightControls=function(){var b=this,c=this.widgetSelectors.join(",");a(c).attr("title",this.l10n.widgetTooltip),a(document).on("mouseenter",c,function(){b.preview.send("highlight-widget-control",a(this).prop("id"))}),a(document).on("click",c,function(c){c.shiftKey&&(c.preventDefault(),b.preview.send("focus-widget-control",a(this).prop("id")))})},e.parseWidgetId=function(a){var b,c={idBase:"",number:null};return b=a.match(/^(.+)-(\d+)$/),b?(c.idBase=b[1],c.number=parseInt(b[2],10)):c.idBase=a,c},e.parseWidgetSettingId=function(a){var b,c={idBase:"",number:null};return(b=a.match(/^widget_([^\[]+?)(?:\[(\d+)])?$/))?(c.idBase=b[1],b[2]&&(c.number=parseInt(b[2],10)),c):null},e.getWidgetSettingId=function(a){var b,c=this.parseWidgetId(a);return b="widget_"+c.idBase,c.number&&(b+="["+String(c.number)+"]"),b},d.bind("preview-ready",function(){a.extend(e,_wpWidgetCustomizerPreviewSettings),e.init()}),e}(jQuery,_,wp,wp.customize);
\ No newline at end of file
+wp.customize.widgetsPreview=wp.customize.WidgetCustomizerPreview=function(a,b,c,d){var e;return e={renderedSidebars:{},renderedWidgets:{},registeredSidebars:[],registeredWidgets:{},widgetSelectors:[],preview:null,l10n:{widgetTooltip:""},selectiveRefreshableWidgets:{}},e.init=function(){var a=this;a.preview=d.preview,b.isEmpty(a.selectiveRefreshableWidgets)||a.addPartials(),a.buildWidgetSelectors(),a.highlightControls(),a.preview.bind("highlight-widget",a.highlightWidget),d.preview.bind("active",function(){a.highlightControls()})},e.WidgetPartial=d.selectiveRefresh.Partial.extend({initialize:function(a,c){var f,g=this;if(f=a.match(/^widget\[(.+)]$/),!f)throw new Error("Illegal id for widget partial.");g.widgetId=f[1],g.widgetIdParts=e.parseWidgetId(g.widgetId),c=c||{},c.params=b.extend({settings:[e.getWidgetSettingId(g.widgetId)],containerInclusive:!0},c.params||{}),d.selectiveRefresh.Partial.prototype.initialize.call(g,a,c)},refresh:function(){var b,c=this;return e.selectiveRefreshableWidgets[c.widgetIdParts.idBase]?d.selectiveRefresh.Partial.prototype.refresh.call(c):(b=a.Deferred(),b.reject(),c.fallback(),b.promise())},renderContent:function(a){var b=this;d.selectiveRefresh.Partial.prototype.renderContent.call(b,a)&&(d.preview.send("widget-updated",b.widgetId),d.selectiveRefresh.trigger("widget-updated",b))}}),e.SidebarPartial=d.selectiveRefresh.Partial.extend({initialize:function(a,c){var e,f=this;if(e=a.match(/^sidebar\[(.+)]$/),!e)throw new Error("Illegal id for sidebar partial.");if(f.sidebarId=e[1],c=c||{},c.params=b.extend({settings:["sidebars_widgets["+f.sidebarId+"]"]},c.params||{}),d.selectiveRefresh.Partial.prototype.initialize.call(f,a,c),!f.params.sidebarArgs)throw new Error("The sidebarArgs param was not provided.");if(f.params.settings.length>1)throw new Error("Expected SidebarPartial to only have one associated setting")},ready:function(){var a=this;b.each(a.settings(),function(c){d(c).bind(b.bind(a.handleSettingChange,a))}),d.selectiveRefresh.bind("partial-content-rendered",function(c){var f=c.partial.extended(e.WidgetPartial)&&-1!==b.indexOf(a.getWidgetIds(),c.partial.widgetId);f&&d.selectiveRefresh.trigger("sidebar-updated",a)}),d.bind("change",function(c){var d,f;f=e.parseWidgetSettingId(c.id),f&&(d=f.idBase,f.number&&(d+="-"+String(f.number)),-1!==b.indexOf(a.getWidgetIds(),d)&&a.ensureWidgetPlacementContainers(d))})},findDynamicSidebarBoundaryNodes:function(){var a,c,d=this,e={};return a=/^(dynamic_sidebar_before|dynamic_sidebar_after):(.+):(\d+)$/,c=function(f){b.each(f,function(f){var g;if(8===f.nodeType){if(g=f.nodeValue.match(a),!g||g[2]!==d.sidebarId)return;b.isUndefined(e[g[3]])&&(e[g[3]]={before:null,after:null,instanceNumber:parseInt(g[3],10)}),"dynamic_sidebar_before"===g[1]?e[g[3]].before=f:e[g[3]].after=f}else 1===f.nodeType&&c(f.childNodes)})},c(document.body.childNodes),b.values(e)},placements:function(){var a=this;return b.map(a.findDynamicSidebarBoundaryNodes(),function(b){return new d.selectiveRefresh.Placement({partial:a,container:null,startNode:b.before,endNode:b.after,context:{instanceNumber:b.instanceNumber}})})},getWidgetIds:function(){var a,c,e=this;if(a=e.settings()[0],!a)throw new Error("Missing associated setting.");if(!d.has(a))throw new Error("Setting does not exist.");if(c=d(a).get(),!b.isArray(c))throw new Error("Expected setting to be array of widget IDs");return c.slice(0)},reflowWidgets:function(){var a,c,e,f=this,g=[];return c=f.getWidgetIds(),a=f.placements(),e={},b.each(c,function(a){var b=d.selectiveRefresh.partial("widget["+a+"]");b&&(e[a]=b)}),b.each(a,function(a){var c,f=[],h=!1,i=-1;b.each(e,function(d){b.each(d.placements(),function(b){a.context.instanceNumber===b.context.sidebar_instance_number&&(c=b.container.index(),f.push({partial:d,placement:b,position:c}),i>c&&(h=!0),i=c)})}),h&&(b.each(f,function(b){a.endNode.parentNode.insertBefore(b.placement.container[0],a.endNode),d.selectiveRefresh.trigger("partial-content-moved",b.placement)}),g.push(a))}),g.length>0&&d.selectiveRefresh.trigger("sidebar-updated",f),g},ensureWidgetPlacementContainers:function(c){var f,g=this,h=!1,i="widget["+c+"]";return f=d.selectiveRefresh.partial(i),f||(f=new e.WidgetPartial(i,{params:{}}),d.selectiveRefresh.partial.add(f.id,f)),b.each(g.placements(),function(d){var e,i;e=b.find(f.placements(),function(a){return a.context.sidebar_instance_number===d.context.instanceNumber}),e||(i=a(g.params.sidebarArgs.before_widget.replace(/%1\$s/g,c).replace(/%2\$s/g,"widget")+g.params.sidebarArgs.after_widget),i[0]&&(i.attr("data-customize-partial-id",f.id),i.attr("data-customize-partial-type","widget"),i.attr("data-customize-widget-id",c),i.data("customize-partial-placement-context",{sidebar_id:g.sidebarId,sidebar_instance_number:d.context.instanceNumber}),d.endNode.parentNode.insertBefore(i[0],d.endNode),h=!0))}),h&&g.reflowWidgets(),f},handleSettingChange:function(a,c){var e,f,g,h=this,i=[];return(e=c.length>0&&0===a.length||a.length>0&&0===c.length)?void h.fallback():(f=b.difference(c,a),b.each(f,function(a){var c=d.selectiveRefresh.partial("widget["+a+"]");c&&b.each(c.placements(),function(a){var b=a.context.sidebar_id===h.sidebarId||a.context.sidebar_args&&a.context.sidebar_args.id===h.sidebarId;b&&a.container.remove()})}),g=b.difference(a,c),b.each(g,function(a){var b=h.ensureWidgetPlacementContainers(a);i.push(b)}),b.each(i,function(a){a.refresh()}),void d.selectiveRefresh.trigger("sidebar-updated",h))},refresh:function(){var c=this,e=a.Deferred();return e.fail(function(){c.fallback()}),0===c.placements().length?e.reject():(b.each(c.reflowWidgets(),function(a){d.selectiveRefresh.trigger("partial-content-rendered",a)}),e.resolve()),e.promise()}}),d.selectiveRefresh.partialConstructor.sidebar=e.SidebarPartial,d.selectiveRefresh.partialConstructor.widget=e.WidgetPartial,e.addPartials=function(){b.each(e.registeredSidebars,function(a){var b,c="sidebar["+a.id+"]";b=d.selectiveRefresh.partial(c),b||(b=new e.SidebarPartial(c,{params:{sidebarArgs:a}}),d.selectiveRefresh.partial.add(b.id,b))})},e.buildWidgetSelectors=function(){var b=this;a.each(b.registeredSidebars,function(c,d){var e,f,g,h=[d.before_widget,d.before_title,d.after_title,d.after_widget].join("");e=a(h),f=e.prop("tagName")||"",g=e.prop("className")||"",g&&(g=g.replace(/\S*%[12]\$s\S*/g,""),g=g.replace(/^\s+|\s+$/g,""),g&&(f+="."+g.split(/\s+/).join(".")),b.widgetSelectors.push(f))})},e.highlightWidget=function(b){var c=a(document.body),d=a("#"+b);c.find(".widget-customizer-highlighted-widget").removeClass("widget-customizer-highlighted-widget"),d.addClass("widget-customizer-highlighted-widget"),setTimeout(function(){d.removeClass("widget-customizer-highlighted-widget")},500)},e.highlightControls=function(){var b=this,c=this.widgetSelectors.join(",");d.settings.channel&&(a(c).attr("title",this.l10n.widgetTooltip),a(document).on("mouseenter",c,function(){b.preview.send("highlight-widget-control",a(this).prop("id"))}),a(document).on("click",c,function(c){c.shiftKey&&(c.preventDefault(),b.preview.send("focus-widget-control",a(this).prop("id")))}))},e.parseWidgetId=function(a){var b,c={idBase:"",number:null};return b=a.match(/^(.+)-(\d+)$/),b?(c.idBase=b[1],c.number=parseInt(b[2],10)):c.idBase=a,c},e.parseWidgetSettingId=function(a){var b,c={idBase:"",number:null};return(b=a.match(/^widget_([^\[]+?)(?:\[(\d+)])?$/))?(c.idBase=b[1],b[2]&&(c.number=parseInt(b[2],10)),c):null},e.getWidgetSettingId=function(a){var b,c=this.parseWidgetId(a);return b="widget_"+c.idBase,c.number&&(b+="["+String(c.number)+"]"),b},d.bind("preview-ready",function(){a.extend(e,_wpWidgetCustomizerPreviewSettings),e.init()}),e}(jQuery,_,wp,wp.customize);
\ No newline at end of file
diff --git a/wp-includes/js/customize-preview.js b/wp-includes/js/customize-preview.js
index 1d61ba33e3..22a9e4ec1f 100644
--- a/wp-includes/js/customize-preview.js
+++ b/wp-includes/js/customize-preview.js
@@ -3,7 +3,67 @@
  */
 (function( exports, $ ){
 	var api = wp.customize,
-		debounce;
+		debounce,
+		currentHistoryState = {};
+
+	/*
+	 * Capture the state that is passed into history.replaceState() and history.pushState()
+	 * and also which is returned in the popstate event so that when the changeset_uuid
+	 * gets updated when transitioning to a new changeset there the current state will
+	 * be supplied in the call to history.replaceState().
+	 */
+	( function( history ) {
+		var injectUrlWithState;
+
+		if ( ! history.replaceState ) {
+			return;
+		}
+
+		/**
+		 * Amend the supplied URL with the customized state.
+		 *
+		 * @since 4.7.0
+		 * @access private
+		 *
+		 * @param {string} url URL.
+		 * @returns {string} URL with customized state.
+		 */
+		injectUrlWithState = function( url ) {
+			var urlParser, queryParams;
+			urlParser = document.createElement( 'a' );
+			urlParser.href = url;
+			queryParams = api.utils.parseQueryString( urlParser.search.substr( 1 ) );
+
+			queryParams.customize_changeset_uuid = api.settings.changeset.uuid;
+			if ( ! api.settings.theme.active ) {
+				queryParams.customize_theme = api.settings.theme.stylesheet;
+			}
+			if ( api.settings.theme.channel ) {
+				queryParams.customize_messenger_channel = api.settings.channel;
+			}
+			urlParser.search = $.param( queryParams );
+			return url;
+		};
+
+		history.replaceState = ( function( nativeReplaceState ) {
+			return function historyReplaceState( data, title, url ) {
+				currentHistoryState = data;
+				return nativeReplaceState.call( history, data, title, injectUrlWithState( url ) );
+			};
+		} )( history.replaceState );
+
+		history.pushState = ( function( nativePushState ) {
+			return function historyPushState( data, title, url ) {
+				currentHistoryState = data;
+				return nativePushState.call( history, data, title, injectUrlWithState( url ) );
+			};
+		} )( history.pushState );
+
+		window.addEventListener( 'popstate', function( event ) {
+			currentHistoryState = event.state;
+		} );
+
+	}( history ) );
 
 	/**
 	 * Returns a debounced version of the function.
@@ -37,38 +97,73 @@
 		 * @param {object} options - Extend any instance parameter or method with this object.
 		 */
 		initialize: function( params, options ) {
-			var self = this;
+			var preview = this, urlParser = document.createElement( 'a' );
 
-			api.Messenger.prototype.initialize.call( this, params, options );
+			api.Messenger.prototype.initialize.call( preview, params, options );
 
-			this.body = $( document.body );
-			this.body.on( 'click.preview', 'a', function( event ) {
+			urlParser.href = preview.origin();
+			preview.add( 'scheme', urlParser.protocol.replace( /:$/, '' ) );
+
+			preview.body = $( document.body );
+			preview.body.on( 'click.preview', 'a', function( event ) {
 				var link, isInternalJumpLink;
 				link = $( this );
-				isInternalJumpLink = ( '#' === link.attr( 'href' ).substr( 0, 1 ) );
-				event.preventDefault();
 
-				if ( isInternalJumpLink && '#' !== link.attr( 'href' ) ) {
-					$( link.attr( 'href' ) ).each( function() {
-						this.scrollIntoView();
-					} );
+				// No-op if the anchor is not a link.
+				if ( _.isUndefined( link.attr( 'href' ) ) ) {
+					return;
 				}
 
+				isInternalJumpLink = ( '#' === link.attr( 'href' ).substr( 0, 1 ) );
+
+				// Allow internal jump links to behave normally without preventing default.
+				if ( isInternalJumpLink ) {
+					return;
+				}
+
+				// If the link is not previewable, prevent the browser from navigating to it.
+				if ( ! api.isLinkPreviewable( link[0] ) ) {
+					wp.a11y.speak( api.settings.l10n.linkUnpreviewable );
+					event.preventDefault();
+					return;
+				}
+
+				// If not in an iframe, then allow the link click to proceed normally since the state query params are added.
+				if ( ! api.settings.channel ) {
+					return;
+				}
+
+				// Prevent initiating navigating from click and instead rely on sending url message to pane.
+				event.preventDefault();
+
 				/*
 				 * Note the shift key is checked so shift+click on widgets or
 				 * nav menu items can just result on focusing on the corresponding
 				 * control instead of also navigating to the URL linked to.
 				 */
-				if ( event.shiftKey || isInternalJumpLink ) {
+				if ( event.shiftKey ) {
 					return;
 				}
-				self.send( 'scroll', 0 );
-				self.send( 'url', link.prop( 'href' ) );
-			});
 
-			// You cannot submit forms.
-			this.body.on( 'submit.preview', 'form', function( event ) {
-				var urlParser;
+				// Note: It's not relevant to send scroll because sending url message will have the same effect.
+				preview.send( 'url', link.prop( 'href' ) );
+			} );
+
+			preview.body.on( 'submit.preview', 'form', function( event ) {
+				var urlParser = document.createElement( 'a' );
+				urlParser.href = this.action;
+
+				// If the link is not previewable, prevent the browser from navigating to it.
+				if ( 'GET' !== this.method.toUpperCase() || ! api.isLinkPreviewable( urlParser ) ) {
+					wp.a11y.speak( api.settings.l10n.formUnpreviewable );
+					event.preventDefault();
+					return;
+				}
+
+				// If not in an iframe, then allow the form submission to proceed normally with the state inputs injected.
+				if ( ! api.settings.channel ) {
+					return;
+				}
 
 				/*
 				 * If the default wasn't prevented already (in which case the form
@@ -81,30 +176,399 @@
 				 * a no-op, which is the same behavior as when clicking a link to an
 				 * external site in the preview.
 				 */
-				if ( ! event.isDefaultPrevented() && 'GET' === this.method.toUpperCase() ) {
-					urlParser = document.createElement( 'a' );
-					urlParser.href = this.action;
-					if ( urlParser.search.substr( 1 ).length > 1 ) {
+				if ( ! event.isDefaultPrevented() ) {
+					if ( urlParser.search.length > 1 ) {
 						urlParser.search += '&';
 					}
 					urlParser.search += $( this ).serialize();
 					api.preview.send( 'url', urlParser.href );
 				}
 
+				// Prevent default since navigation should be done via sending url message or via JS submit handler.
 				event.preventDefault();
 			});
 
-			this.window = $( window );
-			this.window.on( 'scroll.preview', debounce( function() {
-				self.send( 'scroll', self.window.scrollTop() );
-			}, 200 ));
+			preview.window = $( window );
 
-			this.bind( 'scroll', function( distance ) {
-				self.window.scrollTop( distance );
-			});
+			if ( api.settings.channel ) {
+				preview.window.on( 'scroll.preview', debounce( function() {
+					preview.send( 'scroll', preview.window.scrollTop() );
+				}, 200 ) );
+
+				preview.bind( 'scroll', function( distance ) {
+					preview.window.scrollTop( distance );
+				});
+			}
 		}
 	});
 
+	/**
+	 * Inject the changeset UUID into links in the document.
+	 *
+	 * @since 4.7.0
+	 * @access protected
+	 *
+	 * @access private
+	 * @returns {void}
+	 */
+	api.addLinkPreviewing = function addLinkPreviewing() {
+		var linkSelectors = 'a[href], area';
+
+		// Inject links into initial document.
+		$( document.body ).find( linkSelectors ).each( function() {
+			api.prepareLinkPreview( this );
+		} );
+
+		// Inject links for new elements added to the page.
+		if ( 'undefined' !== typeof MutationObserver ) {
+			api.mutationObserver = new MutationObserver( function( mutations ) {
+				_.each( mutations, function( mutation ) {
+					$( mutation.target ).find( linkSelectors ).each( function() {
+						api.prepareLinkPreview( this );
+					} );
+				} );
+			} );
+			api.mutationObserver.observe( document.documentElement, {
+				childList: true,
+				subtree: true
+			} );
+		} else {
+
+			// If mutation observers aren't available, fallback to just-in-time injection.
+			$( document.documentElement ).on( 'click focus mouseover', linkSelectors, function() {
+				api.prepareLinkPreview( this );
+			} );
+		}
+	};
+
+	/**
+	 * Should the supplied link is previewable.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 *
+	 * @param {HTMLAnchorElement|HTMLAreaElement} element Link element.
+	 * @param {string} element.search Query string.
+	 * @param {string} element.pathname Path.
+	 * @param {string} element.hostname Hostname.
+	 * @param {object} [options]
+	 * @param {object} [options.allowAdminAjax=false] Allow admin-ajax.php requests.
+	 * @returns {boolean} Is appropriate for changeset link.
+	 */
+	api.isLinkPreviewable = function isLinkPreviewable( element, options ) {
+		var hasMatchingHost, urlParser, args;
+
+		args = _.extend( {}, { allowAdminAjax: false }, options || {} );
+
+		if ( 'javascript:' === element.protocol ) { // jshint ignore:line
+			return true;
+		}
+
+		// Only web URLs can be previewed.
+		if ( 'https:' !== element.protocol && 'http:' !== element.protocol ) {
+			return false;
+		}
+
+		urlParser = document.createElement( 'a' );
+		hasMatchingHost = ! _.isUndefined( _.find( api.settings.url.allowed, function( allowedUrl ) {
+			urlParser.href = allowedUrl;
+			if ( urlParser.hostname === element.hostname && urlParser.protocol === element.protocol ) {
+				return true;
+			}
+			return false;
+		} ) );
+		if ( ! hasMatchingHost ) {
+			return false;
+		}
+
+		// Skip wp login and signup pages.
+		if ( /\/wp-(login|signup)\.php$/.test( element.pathname ) ) {
+			return false;
+		}
+
+		// Allow links to admin ajax as faux frontend URLs.
+		if ( /\/wp-admin\/admin-ajax\.php$/.test( element.pathname ) ) {
+			return args.allowAdminAjax;
+		}
+
+		// Disallow links to admin, includes, and content.
+		if ( /\/wp-(admin|includes|content)(\/|$)/.test( element.pathname ) ) {
+			return false;
+		}
+
+		return true;
+	};
+
+	/**
+	 * Inject the customize_changeset_uuid query param into links on the frontend.
+	 *
+	 * @since 4.7.0
+	 * @access protected
+	 *
+	 * @param {HTMLAnchorElement|HTMLAreaElement} element Link element.
+	 * @param {object} element.search Query string.
+	 * @returns {void}
+	 */
+	api.prepareLinkPreview = function prepareLinkPreview( element ) {
+		var queryParams;
+
+		// Skip links in admin bar.
+		if ( $( element ).closest( '#wpadminbar' ).length ) {
+			return;
+		}
+
+		// Ignore links with href="#" or href="#id".
+		if ( '#' === $( element ).attr( 'href' ).substr( 0, 1 ) ) {
+			return;
+		}
+
+		// Make sure links in preview use HTTPS if parent frame uses HTTPS.
+		if ( 'https' === api.preview.scheme.get() && 'http:' === element.protocol && -1 !== api.settings.url.allowedHosts.indexOf( element.hostname ) ) {
+			element.protocol = 'https:';
+		}
+
+		if ( ! api.isLinkPreviewable( element ) ) {
+			$( element ).addClass( 'customize-unpreviewable' );
+			return;
+		}
+		$( element ).removeClass( 'customize-unpreviewable' );
+
+		queryParams = api.utils.parseQueryString( element.search.substring( 1 ) );
+		queryParams.customize_changeset_uuid = api.settings.changeset.uuid;
+		if ( ! api.settings.theme.active ) {
+			queryParams.customize_theme = api.settings.theme.stylesheet;
+		}
+		if ( api.settings.channel ) {
+			queryParams.customize_messenger_channel = api.settings.channel;
+		}
+		element.search = $.param( queryParams );
+
+		// Prevent links from breaking out of preview iframe.
+		if ( api.settings.channel ) {
+			element.target = '_self';
+		}
+	};
+
+	/**
+	 * Inject the changeset UUID into Ajax requests.
+	 *
+	 * @since 4.7.0
+	 * @access protected
+	 *
+	 * @return {void}
+	 */
+	api.addRequestPreviewing = function addRequestPreviewing() {
+
+		/**
+		 * Rewrite Ajax requests to inject customizer state.
+		 *
+		 * @param {object} options Options.
+		 * @param {string} options.type Type.
+		 * @param {string} options.url URL.
+		 * @param {object} originalOptions Original options.
+		 * @param {XMLHttpRequest} xhr XHR.
+		 * @returns {void}
+		 */
+		var prefilterAjax = function( options, originalOptions, xhr ) {
+			var urlParser, queryParams, requestMethod, dirtyValues = {};
+			urlParser = document.createElement( 'a' );
+			urlParser.href = options.url;
+
+			// Abort if the request is not for this site.
+			if ( ! api.isLinkPreviewable( urlParser, { allowAdminAjax: true } ) ) {
+				return;
+			}
+			queryParams = api.utils.parseQueryString( urlParser.search.substring( 1 ) );
+
+			// Note that _dirty flag will be cleared with changeset updates.
+			api.each( function( setting ) {
+				if ( setting._dirty ) {
+					dirtyValues[ setting.id ] = setting.get();
+				}
+			} );
+
+			if ( ! _.isEmpty( dirtyValues ) ) {
+				requestMethod = options.type.toUpperCase();
+
+				// Override underlying request method to ensure unsaved changes to changeset can be included (force Backbone.emulateHTTP).
+				if ( 'POST' !== requestMethod ) {
+					xhr.setRequestHeader( 'X-HTTP-Method-Override', requestMethod );
+					queryParams._method = requestMethod;
+					options.type = 'POST';
+				}
+
+				// Amend the post data with the customized values.
+				if ( options.data ) {
+					options.data += '&';
+				} else {
+					options.data = '';
+				}
+				options.data += $.param( {
+					customized: JSON.stringify( dirtyValues )
+				} );
+			}
+
+			// Include customized state query params in URL.
+			queryParams.customize_changeset_uuid = api.settings.changeset.uuid;
+			if ( ! api.settings.theme.active ) {
+				queryParams.customize_theme = api.settings.theme.stylesheet;
+			}
+			urlParser.search = $.param( queryParams );
+			options.url = urlParser.href;
+		};
+
+		$.ajaxPrefilter( prefilterAjax );
+	};
+
+	/**
+	 * Inject changeset UUID into forms, allowing preview to persist through submissions.
+	 *
+	 * @since 4.7.0
+	 * @access protected
+	 *
+	 * @returns {void}
+	 */
+	api.addFormPreviewing = function addFormPreviewing() {
+
+		// Inject inputs for forms in initial document.
+		$( document.body ).find( 'form' ).each( function() {
+			api.prepareFormPreview( this );
+		} );
+
+		// Inject inputs for new forms added to the page.
+		if ( 'undefined' !== typeof MutationObserver ) {
+			api.mutationObserver = new MutationObserver( function( mutations ) {
+				_.each( mutations, function( mutation ) {
+					$( mutation.target ).find( 'form' ).each( function() {
+						api.prepareFormPreview( this );
+					} );
+				} );
+			} );
+			api.mutationObserver.observe( document.documentElement, {
+				childList: true,
+				subtree: true
+			} );
+		}
+	};
+
+	/**
+	 * Inject changeset into form inputs.
+	 *
+	 * @since 4.7.0
+	 * @access protected
+	 *
+	 * @param {HTMLFormElement} form Form.
+	 * @returns {void}
+	 */
+	api.prepareFormPreview = function prepareFormPreview( form ) {
+		var urlParser, stateParams = {};
+
+		if ( ! form.action ) {
+			form.action = location.href;
+		}
+
+		urlParser = document.createElement( 'a' );
+		urlParser.href = form.action;
+
+		// Make sure forms in preview use HTTPS if parent frame uses HTTPS.
+		if ( 'https' === api.preview.scheme.get() && 'http:' === urlParser.protocol && -1 !== api.settings.url.allowedHosts.indexOf( urlParser.hostname ) ) {
+			urlParser.protocol = 'https:';
+			form.action = urlParser.href;
+		}
+
+		if ( 'GET' !== form.method.toUpperCase() || ! api.isLinkPreviewable( urlParser ) ) {
+			$( form ).addClass( 'customize-unpreviewable' );
+			return;
+		}
+		$( form ).removeClass( 'customize-unpreviewable' );
+
+		stateParams.customize_changeset_uuid = api.settings.changeset.uuid;
+		if ( ! api.settings.theme.active ) {
+			stateParams.customize_theme = api.settings.theme.stylesheet;
+		}
+		if ( api.settings.channel ) {
+			stateParams.customize_messenger_channel = api.settings.channel;
+		}
+
+		_.each( stateParams, function( value, name ) {
+			var input = $( form ).find( 'input[name="' + name + '"]' );
+			if ( input.length ) {
+				input.val( value );
+			} else {
+				$( form ).prepend( $( '<input>', {
+					type: 'hidden',
+					name: name,
+					value: value
+				} ) );
+			}
+		} );
+
+		// Prevent links from breaking out of preview iframe.
+		if ( api.settings.channel ) {
+			form.target = '_self';
+		}
+	};
+
+	/**
+	 * Watch current URL and send keep-alive (heartbeat) messages to the parent.
+	 *
+	 * Keep the customizer pane notified that the preview is still alive
+	 * and that the user hasn't navigated to a non-customized URL.
+	 *
+	 * @since 4.7.0
+	 * @access protected
+	 */
+	api.keepAliveCurrentUrl = ( function() {
+		var previousPathName = location.pathname,
+			previousQueryString = location.search.substr( 1 ),
+			previousQueryParams = null,
+			stateQueryParams = [ 'customize_theme', 'customize_changeset_uuid', 'customize_messenger_channel' ];
+
+		return function keepAliveCurrentUrl() {
+			var urlParser, currentQueryParams;
+
+			// Short-circuit with keep-alive if previous URL is identical (as is normal case).
+			if ( previousQueryString === location.search.substr( 1 ) && previousPathName === location.pathname ) {
+				api.preview.send( 'keep-alive' );
+				return;
+			}
+
+			urlParser = document.createElement( 'a' );
+			if ( null === previousQueryParams ) {
+				urlParser.search = previousQueryString;
+				previousQueryParams = api.utils.parseQueryString( previousQueryString );
+				_.each( stateQueryParams, function( name ) {
+					delete previousQueryParams[ name ];
+				} );
+			}
+
+			// Determine if current URL minus customized state params and URL hash.
+			urlParser.href = location.href;
+			currentQueryParams = api.utils.parseQueryString( urlParser.search.substr( 1 ) );
+			_.each( stateQueryParams, function( name ) {
+				delete currentQueryParams[ name ];
+			} );
+
+			if ( previousPathName !== location.pathname || ! _.isEqual( previousQueryParams, currentQueryParams ) ) {
+				urlParser.search = $.param( currentQueryParams );
+				urlParser.hash = '';
+				api.settings.url.self = urlParser.href;
+				api.preview.send( 'ready', {
+					currentUrl: api.settings.url.self,
+					activePanels: api.settings.activePanels,
+					activeSections: api.settings.activeSections,
+					activeControls: api.settings.activeControls,
+					settingValidities: api.settings.settingValidities
+				} );
+			} else {
+				api.preview.send( 'keep-alive' );
+			}
+			previousQueryParams = currentQueryParams;
+			previousQueryString = location.search.substr( 1 );
+			previousPathName = location.pathname;
+		};
+	} )();
+
 	$( function() {
 		var bg, setValue;
 
@@ -118,6 +582,10 @@
 			channel: api.settings.channel
 		});
 
+		api.addLinkPreviewing();
+		api.addRequestPreviewing();
+		api.addFormPreviewing();
+
 		/**
 		 * Create/update a setting value.
 		 *
@@ -171,15 +639,47 @@
 			api.preview.send( 'nonce', api.settings.nonce );
 
 			api.preview.send( 'documentTitle', document.title );
+
+			// Send scroll in case of loading via non-refresh.
+			api.preview.send( 'scroll', $( window ).scrollTop() );
 		});
 
 		api.preview.bind( 'saved', function( response ) {
+
+			if ( response.next_changeset_uuid ) {
+				api.settings.changeset.uuid = response.next_changeset_uuid;
+
+				// Update UUIDs in links and forms.
+				$( document.body ).find( 'a[href], area' ).each( function() {
+					api.prepareLinkPreview( this );
+				} );
+				$( document.body ).find( 'form' ).each( function() {
+					api.prepareFormPreview( this );
+				} );
+
+				/*
+				 * Replace the UUID in the URL. Note that the wrapped history.replaceState()
+				 * will handle injecting the current api.settings.changeset.uuid into the URL,
+				 * so this is merely to trigger that logic.
+				 */
+				if ( history.replaceState ) {
+					history.replaceState( currentHistoryState, '', location.href );
+				}
+			}
+
 			api.trigger( 'saved', response );
 		} );
 
-		api.bind( 'saved', function() {
-			api.each( function( setting ) {
-				setting._dirty = false;
+		/*
+		 * Clear dirty flag for settings when saved to changeset so that they
+		 * won't be needlessly included in selective refresh or ajax requests.
+		 */
+		api.preview.bind( 'changeset-saved', function( data ) {
+			_.each( data.saved_changeset_values, function( value, settingId ) {
+				var setting = api( settingId );
+				if ( setting && _.isEqual( setting.get(), value ) ) {
+					setting._dirty = false;
+				}
 			} );
 		} );
 
@@ -192,12 +692,16 @@
 		 * containers and controls are active.
 		 */
 		api.preview.send( 'ready', {
+			currentUrl: api.settings.url.self,
 			activePanels: api.settings.activePanels,
 			activeSections: api.settings.activeSections,
 			activeControls: api.settings.activeControls,
 			settingValidities: api.settings.settingValidities
 		} );
 
+		// Send ready when URL changes via JS.
+		setInterval( api.keepAliveCurrentUrl, api.settings.timeouts.keepAliveSend );
+
 		// Display a loading indicator when preview is reloading, and remove on failure.
 		api.preview.bind( 'loading-initiated', function () {
 			$( 'body' ).addClass( 'wp-customizer-unloading' );
diff --git a/wp-includes/js/customize-preview.min.js b/wp-includes/js/customize-preview.min.js
index efc2787adf..affc41e769 100644
--- a/wp-includes/js/customize-preview.min.js
+++ b/wp-includes/js/customize-preview.min.js
@@ -1 +1 @@
-!function(a,b){var c,d=wp.customize;c=function(a,b,c){var d;return function(){var e=arguments;c=c||this,clearTimeout(d),d=setTimeout(function(){d=null,a.apply(c,e)},b)}},d.Preview=d.Messenger.extend({initialize:function(a,e){var f=this;d.Messenger.prototype.initialize.call(this,a,e),this.body=b(document.body),this.body.on("click.preview","a",function(a){var c,d;c=b(this),d="#"===c.attr("href").substr(0,1),a.preventDefault(),d&&"#"!==c.attr("href")&&b(c.attr("href")).each(function(){this.scrollIntoView()}),a.shiftKey||d||(f.send("scroll",0),f.send("url",c.prop("href")))}),this.body.on("submit.preview","form",function(a){var c;a.isDefaultPrevented()||"GET"!==this.method.toUpperCase()||(c=document.createElement("a"),c.href=this.action,c.search.substr(1).length>1&&(c.search+="&"),c.search+=b(this).serialize(),d.preview.send("url",c.href)),a.preventDefault()}),this.window=b(window),this.window.on("scroll.preview",c(function(){f.send("scroll",f.window.scrollTop())},200)),this.bind("scroll",function(a){f.window.scrollTop(a)})}}),b(function(){var a,c;d.settings=window._wpCustomizeSettings,d.settings&&(d.preview=new d.Preview({url:window.location.href,channel:d.settings.channel}),c=function(a,b,c){var e=d(a);e?e.set(b):(c=c||!1,e=d.create(a,b,{id:a}),c&&(e._dirty=!0))},d.preview.bind("settings",function(a){b.each(a,c)}),d.preview.trigger("settings",d.settings.values),b.each(d.settings._dirty,function(a,b){var c=d(b);c&&(c._dirty=!0)}),d.preview.bind("setting",function(a){var b=!0;c.apply(null,a.concat(b))}),d.preview.bind("sync",function(a){b.each(a,function(a,b){d.preview.trigger(a,b)}),d.preview.send("synced")}),d.preview.bind("active",function(){d.preview.send("nonce",d.settings.nonce),d.preview.send("documentTitle",document.title)}),d.preview.bind("saved",function(a){d.trigger("saved",a)}),d.bind("saved",function(){d.each(function(a){a._dirty=!1})}),d.preview.bind("nonce-refresh",function(a){b.extend(d.settings.nonce,a)}),d.preview.send("ready",{activePanels:d.settings.activePanels,activeSections:d.settings.activeSections,activeControls:d.settings.activeControls,settingValidities:d.settings.settingValidities}),d.preview.bind("loading-initiated",function(){b("body").addClass("wp-customizer-unloading")}),d.preview.bind("loading-failed",function(){b("body").removeClass("wp-customizer-unloading")}),a=b.map(["color","image","position_x","repeat","attachment"],function(a){return"background_"+a}),d.when.apply(d,a).done(function(a,c,d,e,f){var g,h=b(document.body),i=b("head"),j=b("#custom-background-css");g=function(){var g="";h.toggleClass("custom-background",!(!a()&&!c())),a()&&(g+="background-color: "+a()+";"),c()&&(g+='background-image: url("'+c()+'");',g+="background-position: top "+d()+";",g+="background-repeat: "+e()+";",g+="background-attachment: "+f()+";"),j.remove(),j=b('<style type="text/css" id="custom-background-css">body.custom-background { '+g+" }</style>").appendTo(i)},b.each(arguments,function(){this.bind(g)})}),d("custom_logo",function(a){b("body").toggleClass("wp-custom-logo",!!a.get()),a.bind(function(a){b("body").toggleClass("wp-custom-logo",!!a)})}),d.trigger("preview-ready"))})}(wp,jQuery);
\ No newline at end of file
+!function(a,b){var c,d=wp.customize,e={};!function(a){var c;a.replaceState&&(c=function(a){var c,e;return c=document.createElement("a"),c.href=a,e=d.utils.parseQueryString(c.search.substr(1)),e.customize_changeset_uuid=d.settings.changeset.uuid,d.settings.theme.active||(e.customize_theme=d.settings.theme.stylesheet),d.settings.theme.channel&&(e.customize_messenger_channel=d.settings.channel),c.search=b.param(e),a},a.replaceState=function(b){return function(d,f,g){return e=d,b.call(a,d,f,c(g))}}(a.replaceState),a.pushState=function(b){return function(d,f,g){return e=d,b.call(a,d,f,c(g))}}(a.pushState),window.addEventListener("popstate",function(a){e=a.state}))}(history),c=function(a,b,c){var d;return function(){var e=arguments;c=c||this,clearTimeout(d),d=setTimeout(function(){d=null,a.apply(c,e)},b)}},d.Preview=d.Messenger.extend({initialize:function(a,e){var f=this,g=document.createElement("a");d.Messenger.prototype.initialize.call(f,a,e),g.href=f.origin(),f.add("scheme",g.protocol.replace(/:$/,"")),f.body=b(document.body),f.body.on("click.preview","a",function(a){var c,e;return c=b(this),_.isUndefined(c.attr("href"))||(e="#"===c.attr("href").substr(0,1))?void 0:d.isLinkPreviewable(c[0])?void(d.settings.channel&&(a.preventDefault(),a.shiftKey||f.send("url",c.prop("href")))):(wp.a11y.speak(d.settings.l10n.linkUnpreviewable),void a.preventDefault())}),f.body.on("submit.preview","form",function(a){var c=document.createElement("a");return c.href=this.action,"GET"===this.method.toUpperCase()&&d.isLinkPreviewable(c)?void(d.settings.channel&&(a.isDefaultPrevented()||(c.search.length>1&&(c.search+="&"),c.search+=b(this).serialize(),d.preview.send("url",c.href)),a.preventDefault())):(wp.a11y.speak(d.settings.l10n.formUnpreviewable),void a.preventDefault())}),f.window=b(window),d.settings.channel&&(f.window.on("scroll.preview",c(function(){f.send("scroll",f.window.scrollTop())},200)),f.bind("scroll",function(a){f.window.scrollTop(a)}))}}),d.addLinkPreviewing=function(){var a="a[href], area";b(document.body).find(a).each(function(){d.prepareLinkPreview(this)}),"undefined"!=typeof MutationObserver?(d.mutationObserver=new MutationObserver(function(c){_.each(c,function(c){b(c.target).find(a).each(function(){d.prepareLinkPreview(this)})})}),d.mutationObserver.observe(document.documentElement,{childList:!0,subtree:!0})):b(document.documentElement).on("click focus mouseover",a,function(){d.prepareLinkPreview(this)})},d.isLinkPreviewable=function(a,b){var c,e,f;return f=_.extend({},{allowAdminAjax:!1},b||{}),"javascript:"===a.protocol?!0:"https:"!==a.protocol&&"http:"!==a.protocol?!1:(e=document.createElement("a"),c=!_.isUndefined(_.find(d.settings.url.allowed,function(b){return e.href=b,e.hostname===a.hostname&&e.protocol===a.protocol})),c?/\/wp-(login|signup)\.php$/.test(a.pathname)?!1:/\/wp-admin\/admin-ajax\.php$/.test(a.pathname)?f.allowAdminAjax:!/\/wp-(admin|includes|content)(\/|$)/.test(a.pathname):!1)},d.prepareLinkPreview=function(a){var c;if(!b(a).closest("#wpadminbar").length&&"#"!==b(a).attr("href").substr(0,1)){if("https"===d.preview.scheme.get()&&"http:"===a.protocol&&-1!==d.settings.url.allowedHosts.indexOf(a.hostname)&&(a.protocol="https:"),!d.isLinkPreviewable(a))return void b(a).addClass("customize-unpreviewable");b(a).removeClass("customize-unpreviewable"),c=d.utils.parseQueryString(a.search.substring(1)),c.customize_changeset_uuid=d.settings.changeset.uuid,d.settings.theme.active||(c.customize_theme=d.settings.theme.stylesheet),d.settings.channel&&(c.customize_messenger_channel=d.settings.channel),a.search=b.param(c),d.settings.channel&&(a.target="_self")}},d.addRequestPreviewing=function(){var a=function(a,c,e){var f,g,h,i={};f=document.createElement("a"),f.href=a.url,d.isLinkPreviewable(f,{allowAdminAjax:!0})&&(g=d.utils.parseQueryString(f.search.substring(1)),d.each(function(a){a._dirty&&(i[a.id]=a.get())}),_.isEmpty(i)||(h=a.type.toUpperCase(),"POST"!==h&&(e.setRequestHeader("X-HTTP-Method-Override",h),g._method=h,a.type="POST"),a.data?a.data+="&":a.data="",a.data+=b.param({customized:JSON.stringify(i)})),g.customize_changeset_uuid=d.settings.changeset.uuid,d.settings.theme.active||(g.customize_theme=d.settings.theme.stylesheet),f.search=b.param(g),a.url=f.href)};b.ajaxPrefilter(a)},d.addFormPreviewing=function(){b(document.body).find("form").each(function(){d.prepareFormPreview(this)}),"undefined"!=typeof MutationObserver&&(d.mutationObserver=new MutationObserver(function(a){_.each(a,function(a){b(a.target).find("form").each(function(){d.prepareFormPreview(this)})})}),d.mutationObserver.observe(document.documentElement,{childList:!0,subtree:!0}))},d.prepareFormPreview=function(a){var c,e={};return a.action||(a.action=location.href),c=document.createElement("a"),c.href=a.action,"https"===d.preview.scheme.get()&&"http:"===c.protocol&&-1!==d.settings.url.allowedHosts.indexOf(c.hostname)&&(c.protocol="https:",a.action=c.href),"GET"===a.method.toUpperCase()&&d.isLinkPreviewable(c)?(b(a).removeClass("customize-unpreviewable"),e.customize_changeset_uuid=d.settings.changeset.uuid,d.settings.theme.active||(e.customize_theme=d.settings.theme.stylesheet),d.settings.channel&&(e.customize_messenger_channel=d.settings.channel),_.each(e,function(c,d){var e=b(a).find('input[name="'+d+'"]');e.length?e.val(c):b(a).prepend(b("<input>",{type:"hidden",name:d,value:c}))}),void(d.settings.channel&&(a.target="_self"))):void b(a).addClass("customize-unpreviewable")},d.keepAliveCurrentUrl=function(){var a=location.pathname,c=location.search.substr(1),e=null,f=["customize_theme","customize_changeset_uuid","customize_messenger_channel"];return function(){var g,h;return c===location.search.substr(1)&&a===location.pathname?void d.preview.send("keep-alive"):(g=document.createElement("a"),null===e&&(g.search=c,e=d.utils.parseQueryString(c),_.each(f,function(a){delete e[a]})),g.href=location.href,h=d.utils.parseQueryString(g.search.substr(1)),_.each(f,function(a){delete h[a]}),a===location.pathname&&_.isEqual(e,h)?d.preview.send("keep-alive"):(g.search=b.param(h),g.hash="",d.settings.url.self=g.href,d.preview.send("ready",{currentUrl:d.settings.url.self,activePanels:d.settings.activePanels,activeSections:d.settings.activeSections,activeControls:d.settings.activeControls,settingValidities:d.settings.settingValidities})),e=h,c=location.search.substr(1),void(a=location.pathname))}}(),b(function(){var a,c;d.settings=window._wpCustomizeSettings,d.settings&&(d.preview=new d.Preview({url:window.location.href,channel:d.settings.channel}),d.addLinkPreviewing(),d.addRequestPreviewing(),d.addFormPreviewing(),c=function(a,b,c){var e=d(a);e?e.set(b):(c=c||!1,e=d.create(a,b,{id:a}),c&&(e._dirty=!0))},d.preview.bind("settings",function(a){b.each(a,c)}),d.preview.trigger("settings",d.settings.values),b.each(d.settings._dirty,function(a,b){var c=d(b);c&&(c._dirty=!0)}),d.preview.bind("setting",function(a){var b=!0;c.apply(null,a.concat(b))}),d.preview.bind("sync",function(a){b.each(a,function(a,b){d.preview.trigger(a,b)}),d.preview.send("synced")}),d.preview.bind("active",function(){d.preview.send("nonce",d.settings.nonce),d.preview.send("documentTitle",document.title),d.preview.send("scroll",b(window).scrollTop())}),d.preview.bind("saved",function(a){a.next_changeset_uuid&&(d.settings.changeset.uuid=a.next_changeset_uuid,b(document.body).find("a[href], area").each(function(){d.prepareLinkPreview(this)}),b(document.body).find("form").each(function(){d.prepareFormPreview(this)}),history.replaceState&&history.replaceState(e,"",location.href)),d.trigger("saved",a)}),d.preview.bind("changeset-saved",function(a){_.each(a.saved_changeset_values,function(a,b){var c=d(b);c&&_.isEqual(c.get(),a)&&(c._dirty=!1)})}),d.preview.bind("nonce-refresh",function(a){b.extend(d.settings.nonce,a)}),d.preview.send("ready",{currentUrl:d.settings.url.self,activePanels:d.settings.activePanels,activeSections:d.settings.activeSections,activeControls:d.settings.activeControls,settingValidities:d.settings.settingValidities}),setInterval(d.keepAliveCurrentUrl,d.settings.timeouts.keepAliveSend),d.preview.bind("loading-initiated",function(){b("body").addClass("wp-customizer-unloading")}),d.preview.bind("loading-failed",function(){b("body").removeClass("wp-customizer-unloading")}),a=b.map(["color","image","position_x","repeat","attachment"],function(a){return"background_"+a}),d.when.apply(d,a).done(function(a,c,d,e,f){var g,h=b(document.body),i=b("head"),j=b("#custom-background-css");g=function(){var g="";h.toggleClass("custom-background",!(!a()&&!c())),a()&&(g+="background-color: "+a()+";"),c()&&(g+='background-image: url("'+c()+'");',g+="background-position: top "+d()+";",g+="background-repeat: "+e()+";",g+="background-attachment: "+f()+";"),j.remove(),j=b('<style type="text/css" id="custom-background-css">body.custom-background { '+g+" }</style>").appendTo(i)},b.each(arguments,function(){this.bind(g)})}),d("custom_logo",function(a){b("body").toggleClass("wp-custom-logo",!!a.get()),a.bind(function(a){b("body").toggleClass("wp-custom-logo",!!a)})}),d.trigger("preview-ready"))})}(wp,jQuery);
\ No newline at end of file
diff --git a/wp-includes/js/customize-selective-refresh.js b/wp-includes/js/customize-selective-refresh.js
index 6bab103ff9..427a7c3c9b 100644
--- a/wp-includes/js/customize-selective-refresh.js
+++ b/wp-includes/js/customize-selective-refresh.js
@@ -11,8 +11,7 @@ wp.customize.selectiveRefresh = ( function( $, api ) {
 			renderQueryVar: '',
 			l10n: {
 				shiftClickToEdit: ''
-			},
-			refreshBuffer: 250
+			}
 		},
 		currentRequest: null
 	};
@@ -485,8 +484,9 @@ wp.customize.selectiveRefresh = ( function( $, api ) {
 		return {
 			wp_customize: 'on',
 			nonce: api.settings.nonce.preview,
-			theme: api.settings.theme.stylesheet,
-			customized: JSON.stringify( dirtyCustomized )
+			customize_theme: api.settings.theme.stylesheet,
+			customized: JSON.stringify( dirtyCustomized ),
+			customize_changeset_uuid: api.settings.changeset.uuid
 		};
 	};
 
@@ -668,7 +668,7 @@ wp.customize.selectiveRefresh = ( function( $, api ) {
 					self._pendingPartialRequests = {};
 				} );
 			},
-			self.data.refreshBuffer
+			api.settings.timeouts.selectiveRefresh
 		);
 
 		return partialRequest.deferred.promise();
diff --git a/wp-includes/js/customize-selective-refresh.min.js b/wp-includes/js/customize-selective-refresh.min.js
index f45be9d430..a62b14de59 100644
--- a/wp-includes/js/customize-selective-refresh.min.js
+++ b/wp-includes/js/customize-selective-refresh.min.js
@@ -1 +1 @@
-wp.customize.selectiveRefresh=function(a,b){"use strict";var c,d,e;return c={ready:a.Deferred(),data:{partials:{},renderQueryVar:"",l10n:{shiftClickToEdit:""},refreshBuffer:250},currentRequest:null},_.extend(c,b.Events),d=c.Partial=b.Class.extend({id:null,initialize:function(b,c){var d=this;c=c||{},d.id=b,d.params=_.extend({selector:null,settings:[],primarySetting:null,containerInclusive:!1,fallbackRefresh:!0},c.params||{}),d.deferred={},d.deferred.ready=a.Deferred(),d.deferred.ready.done(function(){d.ready()})},ready:function(){var b=this;_.each(_.pluck(b.placements(),"container"),function(b){a(b).attr("title",c.data.l10n.shiftClickToEdit)}),a(document).on("click",b.params.selector,function(c){c.shiftKey&&(c.preventDefault(),_.each(b.placements(),function(d){a(d.container).is(c.currentTarget)&&b.showControl()}))})},placements:function(){var b,c=this;return b=c.params.selector||"",b&&(b+=", "),b+='[data-customize-partial-id="'+c.id+'"]',a(b).map(function(){var b,d=a(this);if(b=d.data("customize-partial-placement-context"),_.isString(b)&&"{"===b.substr(0,1))throw new Error("context JSON parse error");return new e({partial:c,container:d,context:b})}).get()},settings:function(){var a=this;return a.params.settings&&0!==a.params.settings.length?a.params.settings:a.params.primarySetting?[a.params.primarySetting]:[a.id]},isRelatedSetting:function(a){var c=this;return _.isString(a)&&(a=b(a)),a?-1!==_.indexOf(c.settings(),a.id):!1},showControl:function(){var a=this,c=a.params.primarySetting;c||(c=_.first(a.settings())),b.preview.send("focus-control-for-setting",c)},preparePlacement:function(b){a(b.container).addClass("customize-partial-refreshing")},_pendingRefreshPromise:null,refresh:function(){var a,b=this;return a=c.requestPartial(b),b._pendingRefreshPromise||(_.each(b.placements(),function(a){b.preparePlacement(a)}),a.done(function(a){_.each(a,function(a){b.renderContent(a)})}),a.fail(function(a,c){b.fallback(a,c)}),b._pendingRefreshPromise=a,a.always(function(){b._pendingRefreshPromise=null})),a},renderContent:function(b){var d,e,f=this;if(!b.container)return f.fallback(new Error("no_container"),[b]),!1;if(b.container=a(b.container),!1===b.addedContent)return f.fallback(new Error("missing_render"),[b]),!1;if(!_.isString(b.addedContent))return f.fallback(new Error("non_string_content"),[b]),!1;c.orginalDocumentWrite=document.write,document.write=function(){throw new Error(c.data.l10n.badDocumentWrite)};try{if(d=b.addedContent,wp.emoji&&wp.emoji.parse&&!a.contains(document.head,b.container[0])&&(d=wp.emoji.parse(d)),f.params.containerInclusive)e=a(d),b.context=_.extend(b.context,e.data("customize-partial-placement-context")||{}),e.data("customize-partial-placement-context",b.context),b.removedNodes=b.container,b.container=e,b.removedNodes.replaceWith(b.container),b.container.attr("title",c.data.l10n.shiftClickToEdit);else{for(b.removedNodes=document.createDocumentFragment();b.container[0].firstChild;)b.removedNodes.appendChild(b.container[0].firstChild);b.container.html(d)}b.container.removeClass("customize-render-content-error")}catch(g){"undefined"!=typeof console&&console.error&&console.error(f.id,g)}return document.write=c.orginalDocumentWrite,c.orginalDocumentWrite=null,b.container.removeClass("customize-partial-refreshing"),b.container.data("customize-partial-content-rendered",!0),c.trigger("partial-content-rendered",b),!0},fallback:function(){var a=this;a.params.fallbackRefresh&&c.requestFullRefresh()}}),c.Placement=e=b.Class.extend({partial:null,container:null,startNode:null,endNode:null,context:null,addedContent:null,removedNodes:null,initialize:function(b){var c=this;if(b=_.extend({},b||{}),!b.partial||!b.partial.extended(d))throw new Error("Missing partial");b.context=b.context||{},b.container&&(b.container=a(b.container)),_.extend(c,b)}}),c.partialConstructor={},c.partial=new b.Values({defaultConstructor:d}),c.getCustomizeQuery=function(){var a={};return b.each(function(b,c){b._dirty&&(a[c]=b())}),{wp_customize:"on",nonce:b.settings.nonce.preview,theme:b.settings.theme.stylesheet,customized:JSON.stringify(a)}},c._pendingPartialRequests={},c._debouncedTimeoutId=null,c._currentRequest=null,c.requestFullRefresh=function(){b.preview.send("refresh")},c.requestPartial=function(d){var f;return c._debouncedTimeoutId&&(clearTimeout(c._debouncedTimeoutId),c._debouncedTimeoutId=null),c._currentRequest&&(c._currentRequest.abort(),c._currentRequest=null),f=c._pendingPartialRequests[d.id],f&&"pending"===f.deferred.state()||(f={deferred:a.Deferred(),partial:d},c._pendingPartialRequests[d.id]=f),d=null,c._debouncedTimeoutId=setTimeout(function(){var a,d,f,g;c._debouncedTimeoutId=null,a=c.getCustomizeQuery(),f={},d={},_.each(c._pendingPartialRequests,function(a,b){f[b]=a.partial.placements(),c.partial.has(b)?d[b]=_.map(f[b],function(a){return a.context||{}}):a.deferred.rejectWith(a.partial,[new Error("partial_removed"),f[b]])}),a.partials=JSON.stringify(d),a[c.data.renderQueryVar]="1",g=c._currentRequest=wp.ajax.send(null,{data:a,url:b.settings.url.self}),g.done(function(a){c.trigger("render-partials-response",a),a.errors&&"undefined"!=typeof console&&console.warn&&_.each(a.errors,function(a){console.warn(a)}),_.each(c._pendingPartialRequests,function(b,c){var d;_.isArray(a.contents[c])?(d=_.map(a.contents[c],function(a,d){var g=f[c][d];return g?g.addedContent=a:g=new e({partial:b.partial,addedContent:a}),g}),b.deferred.resolveWith(b.partial,[d])):b.deferred.rejectWith(b.partial,[new Error("unrecognized_partial"),f[c]])}),c._pendingPartialRequests={}}),g.fail(function(a,b){"abort"!==b&&(_.each(c._pendingPartialRequests,function(b,c){b.deferred.rejectWith(b.partial,[a,f[c]])}),c._pendingPartialRequests={})})},c.data.refreshBuffer),f.deferred.promise()},c.addPartials=function(b,d){var f;b||(b=document.documentElement),b=a(b),d=_.extend({triggerRendered:!0},d||{}),f=b.find("[data-customize-partial-id]"),b.is("[data-customize-partial-id]")&&(f=f.add(b)),f.each(function(){var b,f,g,h,i,j=a(this);f=j.data("customize-partial-id"),f&&(i=j.data("customize-partial-placement-context")||{},b=c.partial(f),b||(h=j.data("customize-partial-options")||{},h.constructingContainerContext=j.data("customize-partial-placement-context")||{},g=c.partialConstructor[j.data("customize-partial-type")]||c.Partial,b=new g(f,h),c.partial.add(b.id,b)),d.triggerRendered&&!j.data("customize-partial-content-rendered")&&c.trigger("partial-content-rendered",new e({partial:b,context:i,container:j})),j.data("customize-partial-content-rendered",!0))})},b.bind("preview-ready",function(){var d,e,f;_.extend(c.data,_customizePartialRefreshExports),_.each(c.data.partials,function(a,b){var d,e=c.partial(b);e?_.extend(e.params,a):(d=c.partialConstructor[a.type]||c.Partial,e=new d(b,{params:a}),c.partial.add(b,e))}),d=function(a,b){var d=this;c.partial.each(function(c){c.isRelatedSetting(d,a,b)&&c.refresh()})},e=function(a){d.call(a,a(),null),a.bind(d)},f=function(a){d.call(a,null,a()),a.unbind(d)},b.bind("add",e),b.bind("remove",f),b.each(function(a){a.bind(d)}),c.addPartials(document.documentElement,{triggerRendered:!1}),"undefined"!=typeof MutationObserver&&(c.mutationObserver=new MutationObserver(function(b){_.each(b,function(b){c.addPartials(a(b.target))})}),c.mutationObserver.observe(document.documentElement,{childList:!0,subtree:!0})),b.selectiveRefresh.bind("partial-content-rendered",function(a){a.container&&c.addPartials(a.container)}),b.selectiveRefresh.bind("render-partials-response",function(a){a.setting_validities&&b.preview.send("selective-refresh-setting-validities",a.setting_validities)}),b.preview.bind("active",function(){c.partial.each(function(a){a.deferred.ready.resolve()}),c.partial.bind("add",function(a){a.deferred.ready.resolve()})})}),c}(jQuery,wp.customize);
\ No newline at end of file
+wp.customize.selectiveRefresh=function(a,b){"use strict";var c,d,e;return c={ready:a.Deferred(),data:{partials:{},renderQueryVar:"",l10n:{shiftClickToEdit:""}},currentRequest:null},_.extend(c,b.Events),d=c.Partial=b.Class.extend({id:null,initialize:function(b,c){var d=this;c=c||{},d.id=b,d.params=_.extend({selector:null,settings:[],primarySetting:null,containerInclusive:!1,fallbackRefresh:!0},c.params||{}),d.deferred={},d.deferred.ready=a.Deferred(),d.deferred.ready.done(function(){d.ready()})},ready:function(){var b=this;_.each(_.pluck(b.placements(),"container"),function(b){a(b).attr("title",c.data.l10n.shiftClickToEdit)}),a(document).on("click",b.params.selector,function(c){c.shiftKey&&(c.preventDefault(),_.each(b.placements(),function(d){a(d.container).is(c.currentTarget)&&b.showControl()}))})},placements:function(){var b,c=this;return b=c.params.selector||"",b&&(b+=", "),b+='[data-customize-partial-id="'+c.id+'"]',a(b).map(function(){var b,d=a(this);if(b=d.data("customize-partial-placement-context"),_.isString(b)&&"{"===b.substr(0,1))throw new Error("context JSON parse error");return new e({partial:c,container:d,context:b})}).get()},settings:function(){var a=this;return a.params.settings&&0!==a.params.settings.length?a.params.settings:a.params.primarySetting?[a.params.primarySetting]:[a.id]},isRelatedSetting:function(a){var c=this;return _.isString(a)&&(a=b(a)),a?-1!==_.indexOf(c.settings(),a.id):!1},showControl:function(){var a=this,c=a.params.primarySetting;c||(c=_.first(a.settings())),b.preview.send("focus-control-for-setting",c)},preparePlacement:function(b){a(b.container).addClass("customize-partial-refreshing")},_pendingRefreshPromise:null,refresh:function(){var a,b=this;return a=c.requestPartial(b),b._pendingRefreshPromise||(_.each(b.placements(),function(a){b.preparePlacement(a)}),a.done(function(a){_.each(a,function(a){b.renderContent(a)})}),a.fail(function(a,c){b.fallback(a,c)}),b._pendingRefreshPromise=a,a.always(function(){b._pendingRefreshPromise=null})),a},renderContent:function(b){var d,e,f=this;if(!b.container)return f.fallback(new Error("no_container"),[b]),!1;if(b.container=a(b.container),!1===b.addedContent)return f.fallback(new Error("missing_render"),[b]),!1;if(!_.isString(b.addedContent))return f.fallback(new Error("non_string_content"),[b]),!1;c.orginalDocumentWrite=document.write,document.write=function(){throw new Error(c.data.l10n.badDocumentWrite)};try{if(d=b.addedContent,wp.emoji&&wp.emoji.parse&&!a.contains(document.head,b.container[0])&&(d=wp.emoji.parse(d)),f.params.containerInclusive)e=a(d),b.context=_.extend(b.context,e.data("customize-partial-placement-context")||{}),e.data("customize-partial-placement-context",b.context),b.removedNodes=b.container,b.container=e,b.removedNodes.replaceWith(b.container),b.container.attr("title",c.data.l10n.shiftClickToEdit);else{for(b.removedNodes=document.createDocumentFragment();b.container[0].firstChild;)b.removedNodes.appendChild(b.container[0].firstChild);b.container.html(d)}b.container.removeClass("customize-render-content-error")}catch(g){"undefined"!=typeof console&&console.error&&console.error(f.id,g)}return document.write=c.orginalDocumentWrite,c.orginalDocumentWrite=null,b.container.removeClass("customize-partial-refreshing"),b.container.data("customize-partial-content-rendered",!0),c.trigger("partial-content-rendered",b),!0},fallback:function(){var a=this;a.params.fallbackRefresh&&c.requestFullRefresh()}}),c.Placement=e=b.Class.extend({partial:null,container:null,startNode:null,endNode:null,context:null,addedContent:null,removedNodes:null,initialize:function(b){var c=this;if(b=_.extend({},b||{}),!b.partial||!b.partial.extended(d))throw new Error("Missing partial");b.context=b.context||{},b.container&&(b.container=a(b.container)),_.extend(c,b)}}),c.partialConstructor={},c.partial=new b.Values({defaultConstructor:d}),c.getCustomizeQuery=function(){var a={};return b.each(function(b,c){b._dirty&&(a[c]=b())}),{wp_customize:"on",nonce:b.settings.nonce.preview,customize_theme:b.settings.theme.stylesheet,customized:JSON.stringify(a),customize_changeset_uuid:b.settings.changeset.uuid}},c._pendingPartialRequests={},c._debouncedTimeoutId=null,c._currentRequest=null,c.requestFullRefresh=function(){b.preview.send("refresh")},c.requestPartial=function(d){var f;return c._debouncedTimeoutId&&(clearTimeout(c._debouncedTimeoutId),c._debouncedTimeoutId=null),c._currentRequest&&(c._currentRequest.abort(),c._currentRequest=null),f=c._pendingPartialRequests[d.id],f&&"pending"===f.deferred.state()||(f={deferred:a.Deferred(),partial:d},c._pendingPartialRequests[d.id]=f),d=null,c._debouncedTimeoutId=setTimeout(function(){var a,d,f,g;c._debouncedTimeoutId=null,a=c.getCustomizeQuery(),f={},d={},_.each(c._pendingPartialRequests,function(a,b){f[b]=a.partial.placements(),c.partial.has(b)?d[b]=_.map(f[b],function(a){return a.context||{}}):a.deferred.rejectWith(a.partial,[new Error("partial_removed"),f[b]])}),a.partials=JSON.stringify(d),a[c.data.renderQueryVar]="1",g=c._currentRequest=wp.ajax.send(null,{data:a,url:b.settings.url.self}),g.done(function(a){c.trigger("render-partials-response",a),a.errors&&"undefined"!=typeof console&&console.warn&&_.each(a.errors,function(a){console.warn(a)}),_.each(c._pendingPartialRequests,function(b,c){var d;_.isArray(a.contents[c])?(d=_.map(a.contents[c],function(a,d){var g=f[c][d];return g?g.addedContent=a:g=new e({partial:b.partial,addedContent:a}),g}),b.deferred.resolveWith(b.partial,[d])):b.deferred.rejectWith(b.partial,[new Error("unrecognized_partial"),f[c]])}),c._pendingPartialRequests={}}),g.fail(function(a,b){"abort"!==b&&(_.each(c._pendingPartialRequests,function(b,c){b.deferred.rejectWith(b.partial,[a,f[c]])}),c._pendingPartialRequests={})})},b.settings.timeouts.selectiveRefresh),f.deferred.promise()},c.addPartials=function(b,d){var f;b||(b=document.documentElement),b=a(b),d=_.extend({triggerRendered:!0},d||{}),f=b.find("[data-customize-partial-id]"),b.is("[data-customize-partial-id]")&&(f=f.add(b)),f.each(function(){var b,f,g,h,i,j=a(this);f=j.data("customize-partial-id"),f&&(i=j.data("customize-partial-placement-context")||{},b=c.partial(f),b||(h=j.data("customize-partial-options")||{},h.constructingContainerContext=j.data("customize-partial-placement-context")||{},g=c.partialConstructor[j.data("customize-partial-type")]||c.Partial,b=new g(f,h),c.partial.add(b.id,b)),d.triggerRendered&&!j.data("customize-partial-content-rendered")&&c.trigger("partial-content-rendered",new e({partial:b,context:i,container:j})),j.data("customize-partial-content-rendered",!0))})},b.bind("preview-ready",function(){var d,e,f;_.extend(c.data,_customizePartialRefreshExports),_.each(c.data.partials,function(a,b){var d,e=c.partial(b);e?_.extend(e.params,a):(d=c.partialConstructor[a.type]||c.Partial,e=new d(b,{params:a}),c.partial.add(b,e))}),d=function(a,b){var d=this;c.partial.each(function(c){c.isRelatedSetting(d,a,b)&&c.refresh()})},e=function(a){d.call(a,a(),null),a.bind(d)},f=function(a){d.call(a,null,a()),a.unbind(d)},b.bind("add",e),b.bind("remove",f),b.each(function(a){a.bind(d)}),c.addPartials(document.documentElement,{triggerRendered:!1}),"undefined"!=typeof MutationObserver&&(c.mutationObserver=new MutationObserver(function(b){_.each(b,function(b){c.addPartials(a(b.target))})}),c.mutationObserver.observe(document.documentElement,{childList:!0,subtree:!0})),b.selectiveRefresh.bind("partial-content-rendered",function(a){a.container&&c.addPartials(a.container)}),b.selectiveRefresh.bind("render-partials-response",function(a){a.setting_validities&&b.preview.send("selective-refresh-setting-validities",a.setting_validities)}),b.preview.bind("active",function(){c.partial.each(function(a){a.deferred.ready.resolve()}),c.partial.bind("add",function(a){a.deferred.ready.resolve()})})}),c}(jQuery,wp.customize);
\ No newline at end of file
diff --git a/wp-includes/post.php b/wp-includes/post.php
index 405a183119..463c874767 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -111,6 +111,51 @@ function create_initial_post_types() {
 		'query_var' => false,
 	) );
 
+	register_post_type( 'customize_changeset', array(
+		'labels' => array(
+			'name'               => _x( 'Changesets', 'post type general name' ),
+			'singular_name'      => _x( 'Changeset', 'post type singular name' ),
+			'menu_name'          => _x( 'Changesets', 'admin menu' ),
+			'name_admin_bar'     => _x( 'Changeset', 'add new on admin bar' ),
+			'add_new'            => _x( 'Add New', 'Customize Changeset' ),
+			'add_new_item'       => __( 'Add New Changeset' ),
+			'new_item'           => __( 'New Changeset' ),
+			'edit_item'          => __( 'Edit Changeset' ),
+			'view_item'          => __( 'View Changeset' ),
+			'all_items'          => __( 'All Changesets' ),
+			'search_items'       => __( 'Search Changesets' ),
+			'not_found'          => __( 'No changesets found.' ),
+			'not_found_in_trash' => __( 'No changesets found in Trash.' ),
+		),
+		'public' => false,
+		'_builtin' => true, /* internal use only. don't use this when registering your own post type. */
+		'map_meta_cap' => true,
+		'hierarchical' => false,
+		'rewrite' => false,
+		'query_var' => false,
+		'can_export' => false,
+		'delete_with_user' => false,
+		'supports' => array( 'title', 'author' ),
+		'capability_type' => 'customize_changeset',
+		'capabilities' => array(
+			'create_posts' => 'customize',
+			'delete_others_posts' => 'customize',
+			'delete_post' => 'customize',
+			'delete_posts' => 'customize',
+			'delete_private_posts' => 'customize',
+			'delete_published_posts' => 'customize',
+			'edit_others_posts' => 'customize',
+			'edit_post' => 'customize',
+			'edit_posts' => 'customize',
+			'edit_private_posts' => 'customize',
+			'edit_published_posts' => 'do_not_allow',
+			'publish_posts' => 'customize',
+			'read' => 'read',
+			'read_post' => 'customize',
+			'read_private_posts' => 'customize',
+		),
+	) );
+
 	register_post_status( 'publish', array(
 		'label'       => _x( 'Published', 'post status' ),
 		'public'      => true,
diff --git a/wp-includes/script-loader.php b/wp-includes/script-loader.php
index e67997a994..c8ec2c5938 100644
--- a/wp-includes/script-loader.php
+++ b/wp-includes/script-loader.php
@@ -450,7 +450,7 @@ function wp_default_scripts( &$scripts ) {
 
 	$scripts->add( 'customize-base',     "/wp-includes/js/customize-base$suffix.js",     array( 'jquery', 'json2', 'underscore' ), false, 1 );
 	$scripts->add( 'customize-loader',   "/wp-includes/js/customize-loader$suffix.js",   array( 'customize-base' ), false, 1 );
-	$scripts->add( 'customize-preview',  "/wp-includes/js/customize-preview$suffix.js",  array( 'customize-base' ), false, 1 );
+	$scripts->add( 'customize-preview',  "/wp-includes/js/customize-preview$suffix.js",  array( 'wp-a11y', 'customize-base' ), false, 1 );
 	$scripts->add( 'customize-models',   "/wp-includes/js/customize-models.js", array( 'underscore', 'backbone' ), false, 1 );
 	$scripts->add( 'customize-views',    "/wp-includes/js/customize-views.js",  array( 'jquery', 'underscore', 'imgareaselect', 'customize-models', 'media-editor', 'media-views' ), false, 1 );
 	$scripts->add( 'customize-controls', "/wp-admin/js/customize-controls$suffix.js", array( 'customize-base', 'wp-a11y', 'wp-util' ), false, 1 );
diff --git a/wp-includes/theme.php b/wp-includes/theme.php
index c8cf03fe6a..b5b8541a1e 100644
--- a/wp-includes/theme.php
+++ b/wp-includes/theme.php
@@ -2066,9 +2066,9 @@ function check_theme_switched() {
  * Includes and instantiates the WP_Customize_Manager class.
  *
  * Loads the Customizer at plugins_loaded when accessing the customize.php admin
- * page or when any request includes a wp_customize=on param, either as a GET
- * query var or as POST data. This param is a signal for whether to bootstrap
- * the Customizer when WordPress is loading, especially in the Customizer preview
+ * page or when any request includes a wp_customize=on param or a customize_changeset
+ * param (a UUID). This param is a signal for whether to bootstrap the Customizer when
+ * WordPress is loading, especially in the Customizer preview
  * or when making Customizer Ajax requests for widgets or menus.
  *
  * @since 3.4.0
@@ -2076,14 +2076,140 @@ function check_theme_switched() {
  * @global WP_Customize_Manager $wp_customize
  */
 function _wp_customize_include() {
-	if ( ! ( ( isset( $_REQUEST['wp_customize'] ) && 'on' == $_REQUEST['wp_customize'] )
-		|| ( is_admin() && 'customize.php' == basename( $_SERVER['PHP_SELF'] ) )
-	) ) {
+
+	$is_customize_admin_page = ( is_admin() && 'customize.php' == basename( $_SERVER['PHP_SELF'] ) );
+	$should_include = (
+		$is_customize_admin_page
+		||
+		( isset( $_REQUEST['wp_customize'] ) && 'on' == $_REQUEST['wp_customize'] )
+		||
+		( ! empty( $_GET['customize_changeset_uuid'] ) || ! empty( $_POST['customize_changeset_uuid'] ) )
+	);
+
+	if ( ! $should_include ) {
 		return;
 	}
 
-	require_once ABSPATH . WPINC . '/class-wp-customize-manager.php'; 
-	$GLOBALS['wp_customize'] = new WP_Customize_Manager();
+	/*
+	 * Note that wp_unslash() is not being used on the input vars because it is
+	 * called before wp_magic_quotes() gets called. Besides this fact, none of
+	 * the values should contain any characters needing slashes anyway.
+	 */
+	$keys = array( 'changeset_uuid', 'customize_changeset_uuid', 'customize_theme', 'theme', 'customize_messenger_channel' );
+	$input_vars = array_merge(
+		wp_array_slice_assoc( $_GET, $keys ),
+		wp_array_slice_assoc( $_POST, $keys )
+	);
+
+	$theme = null;
+	$changeset_uuid = null;
+	$messenger_channel = null;
+
+	if ( $is_customize_admin_page && isset( $input_vars['changeset_uuid'] ) ) {
+		$changeset_uuid = sanitize_key( $input_vars['changeset_uuid'] );
+	} elseif ( ! empty( $input_vars['customize_changeset_uuid'] ) ) {
+		$changeset_uuid = sanitize_key( $input_vars['customize_changeset_uuid'] );
+	}
+
+	// Note that theme will be sanitized via WP_Theme.
+	if ( $is_customize_admin_page && isset( $input_vars['theme'] ) ) {
+		$theme = $input_vars['theme'];
+	} elseif ( isset( $input_vars['customize_theme'] ) ) {
+		$theme = $input_vars['customize_theme'];
+	}
+	if ( isset( $input_vars['customize_messenger_channel'] ) ) {
+		$messenger_channel = sanitize_key( $input_vars['customize_messenger_channel'] );
+	}
+
+	require_once ABSPATH . WPINC . '/class-wp-customize-manager.php';
+	$GLOBALS['wp_customize'] = new WP_Customize_Manager( compact( 'changeset_uuid', 'theme', 'messenger_channel' ) );
+}
+
+/**
+ * Publish a snapshot's changes.
+ *
+ * @param string  $new_status     New post status.
+ * @param string  $old_status     Old post status.
+ * @param WP_Post $changeset_post Changeset post object.
+ */
+function _wp_customize_publish_changeset( $new_status, $old_status, $changeset_post ) {
+	global $wp_customize;
+
+	$is_publishing_changeset = (
+		'customize_changeset' === $changeset_post->post_type
+		&&
+		'publish' === $new_status
+		&&
+		'publish' !== $old_status
+	);
+	if ( ! $is_publishing_changeset ) {
+		return;
+	}
+
+	if ( empty( $wp_customize ) ) {
+		require_once ABSPATH . WPINC . '/class-wp-customize-manager.php';
+		$wp_customize = new WP_Customize_Manager( $changeset_post->post_name );
+	}
+
+	if ( ! did_action( 'customize_register' ) ) {
+		/*
+		 * When running from CLI or Cron, the customize_register action will need
+		 * to be triggered in order for core, themes, and plugins to register their
+		 * settings. Normally core will add_action( 'customize_register' ) at
+		 * priority 10 to register the core settings, and if any themes/plugins
+		 * also add_action( 'customize_register' ) at the same priority, they
+		 * will have a $wp_customize with those settings registered since they
+		 * call add_action() afterward, normally. However, when manually doing
+		 * the customize_register action after the setup_theme, then the order
+		 * will be reversed for two actions added at priority 10, resulting in
+		 * the core settings no longer being available as expected to themes/plugins.
+		 * So the following manually calls the method that registers the core
+		 * settings up front before doing the action.
+		 */
+		remove_action( 'customize_register', array( $wp_customize, 'register_controls' ) );
+		$wp_customize->register_controls();
+
+		/** This filter is documented in /wp-includes/class-wp-customize-manager.php */
+		do_action( 'customize_register', $wp_customize );
+	}
+	$wp_customize->_publish_changeset_values( $changeset_post->ID ) ;
+
+	/*
+	 * Trash the changeset post if revisions are not enabled. Unpublished
+	 * changesets by default get garbage collected due to the auto-draft status.
+	 * When a changeset post is published, however, it would no longer get cleaned
+	 * out. Ths is a problem when the changeset posts are never displayed anywhere,
+	 * since they would just be endlessly piling up. So here we use the revisions
+	 * feature to indicate whether or not a published changeset should get trashed
+	 * and thus garbage collected.
+	 */
+	if ( ! wp_revisions_enabled( $changeset_post ) ) {
+		wp_trash_post( $changeset_post->ID );
+	}
+}
+
+/**
+ * Filters changeset post data upon insert to ensure post_name is intact.
+ *
+ * This is needed to prevent the post_name from being dropped when the post is
+ * transitioned into pending status by a contributor.
+ *
+ * @since 4.7.0
+ * @see wp_insert_post()
+ *
+ * @param array $post_data          An array of slashed post data.
+ * @param array $supplied_post_data An array of sanitized, but otherwise unmodified post data.
+ * @returns array Filtered data.
+ */
+function _wp_customize_changeset_filter_insert_post_data( $post_data, $supplied_post_data ) {
+	if ( isset( $post_data['post_type'] ) && 'customize_changeset' === $post_data['post_type'] ) {
+
+		// Prevent post_name from being dropped, such as when contributor saves a changeset post as pending.
+		if ( empty( $post_data['post_name'] ) && ! empty( $supplied_post_data['post_name'] ) ) {
+			$post_data['post_name'] = $supplied_post_data['post_name'];
+		}
+	}
+	return $post_data;
 }
 
 /**
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 247d4755c6..e02ecf1353 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-alpha-38809';
+$wp_version = '4.7-alpha-38810';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.