Ticket #41158: 41158.3.patch

src/wp-admin/js/customize-controls.js

@@ -5507 +5507 @@
                         } );
                 } ());
 
+                // Make sure TinyMCE dialogs appear above Customizer UI.
+                $( document ).one( 'wp-before-tinymce-init', function() {
+                        if ( ! window.tinymce.ui.FloatPanel.zIndex || window.tinymce.ui.FloatPanel.zIndex < 500001 ) {
+                                window.tinymce.ui.FloatPanel.zIndex = 500001;
+                        }
+                } );
+
                 api.trigger( 'ready' );
         });
 

src/wp-admin/js/widgets/text-widgets.js

@@ -130 +130 @@
                                         wp.editor.remove( id );
                                 }
 
-                                // Adjust z-index for the customizer.
-                                window.tinymce.ui.FloatPanel.zIndex = 500001;
-
                                 wp.editor.initialize( id, {
                                         tinymce: {
                                                 wpautop: true