diff --git a/wp-includes/customize-controls.php b/wp-admin/customize.php
similarity index 78%
rename from wp-includes/customize-controls.php
rename to wp-admin/customize.php
index 0ca6b0932d..dcc3f96002 100644
--- a/wp-includes/customize-controls.php
+++ b/wp-admin/customize.php
@@ -7,10 +7,19 @@
  * @since 3.4.0
  */
 
-if ( ! defined( 'ABSPATH' ) )
-	die;
+require_once( './admin.php' );
+if ( ! current_user_can( 'edit_theme_options' ) )
+	die( 'Cap check failed' );
 
-global $wp_scripts;
+global $wp_scripts, $wp_customize;
+
+if ( ! $wp_customize->is_preview() )
+	die( 'is_preview() failed' );
+
+wp_reset_vars( array( 'theme' ) );
+
+if ( ! $theme )
+	$theme = get_stylesheet();
 
 $registered = $wp_scripts->registered;
 $wp_scripts = new WP_Scripts;
@@ -33,7 +42,7 @@ do_action( 'customize_controls_enqueue_scripts' );
 wp_user_settings();
 _wp_admin_html_begin();
 
-$admin_title = sprintf( __( '%1$s — WordPress' ), strip_tags( sprintf( __( 'Customize %s' ), $this->theme->display('Name') ) ) );
+$admin_title = sprintf( __( '%1$s — WordPress' ), strip_tags( sprintf( __( 'Customize %s' ), $wp_customize->theme()->display('Name') ) ) );
 ?><title><?php echo $admin_title; ?></title><?php
 
 do_action( 'customize_controls_print_styles' );
@@ -53,22 +62,22 @@ do_action( 'customize_controls_print_scripts' );
 			<div id="customize-info" class="customize-section">
 				<div class="customize-section-title">
 					<span class="preview-notice"><?php _e('You are previewing'); ?></span>
-					<strong class="theme-name"><?php echo $this->theme->display('Name'); ?></strong>
+					<strong class="theme-name"><?php echo $wp_customize->theme()->display('Name'); ?></strong>
 				</div>
 				<div class="customize-section-content">
-					<?php if ( $screenshot = $this->theme->get_screenshot() ) : ?>
+					<?php if ( $screenshot = $wp_customize->theme()->get_screenshot() ) : ?>
 						<img class="theme-screenshot" src="<?php echo esc_url( $screenshot ); ?>" />
 					<?php endif; ?>
 
-					<?php if ( $this->theme->get('Description') ): ?>
-						<div class="theme-description"><?php echo $this->theme->display('Description'); ?></div>
+					<?php if ( $wp_customize->theme()->get('Description') ): ?>
+						<div class="theme-description"><?php echo $wp_customize->theme()->display('Description'); ?></div>
 					<?php endif; ?>
 				</div>
 			</div>
 
 			<div id="customize-theme-controls"><ul>
 				<?php
-				foreach ( $this->sections as $section )
+				foreach ( $wp_customize->sections() as $section )
 					$section->maybe_render();
 				?>
 			</ul></div>
@@ -76,7 +85,7 @@ do_action( 'customize_controls_print_scripts' );
 
 		<div id="customize-footer-actions" class="wp-full-overlay-footer">
 			<?php
-			$save_text = $this->is_current_theme_active() ? __('Save') : __('Save and Activate');
+			$save_text = $wp_customize->is_theme_active() ? __('Save') : __('Save and Activate');
 			submit_button( $save_text, 'primary', 'save', false );
 			?>
 			<img src="<?php echo esc_url( admin_url( 'images/wpspin_light.gif' ) ); ?>" />
@@ -108,8 +117,8 @@ do_action( 'customize_controls_print_scripts' );
 
 	$settings = array(
 		'theme'    => array(
-			'stylesheet' => $this->get_stylesheet(),
-			'active'     => $this->is_current_theme_active(),
+			'stylesheet' => $wp_customize->get_stylesheet(),
+			'active'     => $wp_customize->is_theme_active(),
 		),
 		'url'      => array(
 			'preview'  => esc_url( $preview_url ),
@@ -120,14 +129,14 @@ do_action( 'customize_controls_print_scripts' );
 		'controls' => array(),
 	);
 
-	foreach ( $this->settings as $id => $setting ) {
+	foreach ( $wp_customize->settings() as $id => $setting ) {
 		$settings['settings'][ $id ] = array(
 			'value'     => $setting->js_value(),
 			'transport' => $setting->transport,
 		);
 	}
 
-	foreach ( $this->controls as $id => $control ) {
+	foreach ( $wp_customize->controls() as $id => $control ) {
 		$control->to_json();
 		$settings['controls'][ $id ] = $control->json;
 	}
diff --git a/wp-admin/includes/class-wp-plugins-list-table.php b/wp-admin/includes/class-wp-plugins-list-table.php
index a1ce53abb5..f83642ef35 100644
--- a/wp-admin/includes/class-wp-plugins-list-table.php
+++ b/wp-admin/includes/class-wp-plugins-list-table.php
@@ -69,6 +69,11 @@ class WP_Plugins_List_Table extends WP_List_Table {
 				$current = get_site_transient( 'update_plugins' );
 				foreach ( (array) $plugins['all'] as $plugin_file => $plugin_data ) {
 					if ( isset( $current->response[ $plugin_file ] ) ) {
+						ob_start();
+						var_dump( $current->response[ $plugin_file ] );
+						error_log( $plugin_file . ': ' . ob_get_clean() );
+					}
+					if ( ! empty( $current->response[ $plugin_file ] ) ) {
 						$plugins['all'][ $plugin_file ]['update'] = true;
 						$plugins['upgrade'][ $plugin_file ] = $plugins['all'][ $plugin_file ];
 					}
diff --git a/wp-includes/class-wp-customize.php b/wp-includes/class-wp-customize-manager.php
similarity index 96%
rename from wp-includes/class-wp-customize.php
rename to wp-includes/class-wp-customize-manager.php
index 2ba1f1b930..68bacc4ba8 100644
--- a/wp-includes/class-wp-customize.php
+++ b/wp-includes/class-wp-customize-manager.php
@@ -7,7 +7,7 @@
  * @since 3.4.0
  */
 
-final class WP_Customize {
+final class WP_Customize_Manager {
 	protected $theme;
 	protected $original_stylesheet;
 
@@ -32,7 +32,6 @@ final class WP_Customize {
 		require( ABSPATH . WPINC . '/class-wp-customize-control.php' );
 
 		add_action( 'setup_theme',  array( $this, 'setup_theme' ) );
-		add_action( 'admin_init',   array( $this, 'admin_init' ) );
 		add_action( 'wp_loaded',    array( $this, 'wp_loaded' ) );
 
 		add_action( 'wp_ajax_customize_save', array( $this, 'save' ) );
@@ -68,7 +67,7 @@ final class WP_Customize {
 	 * @since 3.4.0
 	 */
 	public function setup_theme() {
-		if ( ! isset( $_REQUEST['customize'] ) || 'on' != $_REQUEST['customize'] )
+		if ( ! ( isset( $_REQUEST['customize'] ) && 'on' == $_REQUEST['customize'] ) && ! basename( $_SERVER['PHP_SELF'] ) == 'customize.php' )
 			return;
 
 		send_origin_headers();
@@ -90,7 +89,7 @@ final class WP_Customize {
 
 		// Initialize $theme and $original_stylesheet if they do not yet exist.
 		if ( ! isset( $this->theme ) ) {
-			$this->theme = wp_get_theme( $_REQUEST['theme'] );
+			$this->theme = wp_get_theme( isset( $_REQUEST['theme'] ) ? $_REQUEST['theme'] : null );
 			if ( ! $this->theme->exists() ) {
 				$this->theme = false;
 				return;
@@ -144,12 +143,26 @@ final class WP_Customize {
 		do_action( 'stop_previewing_theme', $this );
 	}
 
+	/**
+	 * Generic getter.
+	 *
+	 * @since 3.4.0
+	 *
+	 * @return WP_Theme
+	 */
+	public function __call( $callee, $args ) {
+		if ( in_array( $callee, array( 'theme', 'settings', 'controls', 'sections' ) ) )
+			return $this->$callee;
+	}
+
 	/**
 	 * Checks if the current theme is active.
 	 *
 	 * @since 3.4.0
+	 *
+	 * @return bool
 	 */
-	public function is_current_theme_active() {
+	public function is_theme_active() {
 		return $this->get_stylesheet() == $this->original_stylesheet;
 	}
 
@@ -182,7 +195,6 @@ final class WP_Customize {
 			return $setting->sanitize( $this->_post_values[ $setting->id ] );
 	}
 
-
 	/**
 	 * Print javascript settings.
 	 *
@@ -289,32 +301,6 @@ final class WP_Customize {
 		return $this->theme->display('Name');
 	}
 
-	/**
-	 * Trigger save action and load customize controls.
-	 *
-	 * @since 3.4.0
-	 */
-	public function admin_init() {
-		if ( ( defined( 'DOING_AJAX' ) && DOING_AJAX ) )
-			return;
-
-		if ( ! isset( $_GET['customize'] ) || 'on' != $_GET['customize'] )
-			return;
-
-		if ( empty( $_GET['theme'] ) )
-			return;
-
-		if ( ! $this->is_preview() )
-			return;
-
-		if ( ! current_user_can( 'edit_theme_options' ) )
-			return;
-
-		include( ABSPATH . WPINC . '/customize-controls.php' );
-
-		die;
-	}
-
 	/**
 	 * Switch the theme and trigger the save action of each setting.
 	 *
@@ -811,4 +797,4 @@ function sanitize_hexcolor( $color ) {
 		return $color;
 
 	return $color;
-}
\ No newline at end of file
+}
diff --git a/wp-includes/theme.php b/wp-includes/theme.php
index e040e47f50..ee182398ed 100644
--- a/wp-includes/theme.php
+++ b/wp-includes/theme.php
@@ -1566,7 +1566,7 @@ function check_theme_switched() {
 }
 
 /**
- * Includes and instantiates the WP_Customize class.
+ * Includes and instantiates the WP_Customize_Manager class.
  *
  * Fires when ?customize=on.
  *
@@ -1574,12 +1574,12 @@ function check_theme_switched() {
  */
 function _wp_customize_include() {
 	// Load on themes.php or ?customize=on
-	if ( ! ( isset( $_REQUEST['customize'] ) && 'on' == $_REQUEST['customize'] ) )
+	if ( ! ( ( isset( $_REQUEST['customize'] ) && 'on' == $_REQUEST['customize'] ) || 'customize.php' == basename( $_SERVER['PHP_SELF'] ) ) )
 		return;
 
-	require( ABSPATH . WPINC . '/class-wp-customize.php' );
+	require( ABSPATH . WPINC . '/class-wp-customize-manager.php' );
 	// Init Customize class
-	$GLOBALS['wp_customize'] = new WP_Customize;
+	$GLOBALS['wp_customize'] = new WP_Customize_Manager;
 }
 add_action( 'plugins_loaded', '_wp_customize_include' );
 
@@ -1604,5 +1604,5 @@ add_action( 'admin_enqueue_scripts', '_wp_customize_loader_localize' );
  * @since 3.4.0
  */
 function wp_customize_url( $stylesheet ) {
-	return esc_url( admin_url( 'admin.php' ) . '?customize=on&theme=' . $stylesheet );
+	return esc_url( admin_url( 'customize.php' ) . '?theme=' . $stylesheet );
 }
\ No newline at end of file