FIX: On facebook browser, don't close the window but redirect instead

app/views/users/omniauth_callbacks/complete.html.erb

@@ -23,7 +23,14 @@
 
     <script type="text/javascript">
        window.opener.Discourse.authenticationComplete(<%=@auth_result.to_client_hash.to_json.html_safe%>);
-       window.close();
+
+       // On facebook browser, just redirect and don't close
+       var ua = navigator.userAgent || navigator.vendor || window.opera;
+       if ((ua.indexOf("FBAN") > -1) || (ua.indexOf("FBAV") > -1)) {
+         window.location.href = <%= Discourse.base_url.inspect %>;
+       } else {
+         window.close();
+       }
     </script>
   </div>
 </body>