diff -r 346c88efed21 -r 5e2f62d02dcd wp/wp-includes/js/customize-preview-widgets.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/js/customize-preview-widgets.js	Tue Jun 09 03:35:32 2015 +0200
@@ -0,0 +1,129 @@
+(function( wp, $ ){
+
+	if ( ! wp || ! wp.customize ) { return; }
+
+	var api = wp.customize,
+		OldPreview;
+
+	/**
+	 * wp.customize.WidgetCustomizerPreview
+	 *
+	 */
+	api.WidgetCustomizerPreview = {
+		renderedSidebars: {}, // @todo Make rendered a property of the Backbone model
+		renderedWidgets: {}, // @todo Make rendered a property of the Backbone model
+		registeredSidebars: [], // @todo Make a Backbone collection
+		registeredWidgets: {}, // @todo Make array, Backbone collection
+		widgetSelectors: [],
+		preview: null,
+		l10n: {},
+
+		init: function () {
+			var self = this;
+			this.buildWidgetSelectors();
+			this.highlightControls();
+
+			this.preview.bind( 'highlight-widget', self.highlightWidget );
+		},
+
+		/**
+		 * Calculate the selector for the sidebar's widgets based on the registered sidebar's info
+		 */
+		buildWidgetSelectors: function () {
+			var self = this;
+
+			$.each( this.registeredSidebars, function ( i, sidebar ) {
+				var widgetTpl = [
+						sidebar.before_widget.replace('%1$s', '').replace('%2$s', ''),
+						sidebar.before_title,
+						sidebar.after_title,
+						sidebar.after_widget
+					].join(''),
+					emptyWidget,
+					widgetSelector,
+					widgetClasses;
+
+				emptyWidget = $(widgetTpl);
+				widgetSelector = emptyWidget.prop('tagName');
+				widgetClasses = emptyWidget.prop('className');
+
+				// Prevent a rare case when before_widget, before_title, after_title and after_widget is empty.
+				if ( ! widgetClasses ) {
+					return;
+				}
+
+				widgetClasses = widgetClasses.replace(/^\s+|\s+$/g, '');
+
+				if ( widgetClasses ) {
+					widgetSelector += '.' + widgetClasses.split(/\s+/).join('.');
+				}
+				self.widgetSelectors.push(widgetSelector);
+			});
+		},
+
+		/**
+		 * Highlight the widget on widget updates or widget control mouse overs.
+		 *
+		 * @param  {string} widgetId ID of the widget.
+		 */
+		highlightWidget: function( widgetId ) {
+			var $body = $( document.body ),
+				$widget = $( '#' + widgetId );
+
+			$body.find( '.widget-customizer-highlighted-widget' ).removeClass( 'widget-customizer-highlighted-widget' );
+
+			$widget.addClass( 'widget-customizer-highlighted-widget' );
+			setTimeout( function () {
+				$widget.removeClass( 'widget-customizer-highlighted-widget' );
+			}, 500 );
+		},
+
+		/**
+		 * Show a title and highlight widgets on hover. On shift+clicking
+		 * focus the widget control.
+		 */
+		highlightControls: function() {
+			var self = this,
+				selector = this.widgetSelectors.join(',');
+
+			$(selector).attr( 'title', this.l10n.widgetTooltip );
+
+			$(document).on( 'mouseenter', selector, function () {
+				self.preview.send( 'highlight-widget-control', $( this ).prop( 'id' ) );
+			});
+
+			// Open expand the widget control when shift+clicking the widget element
+			$(document).on( 'click', selector, function ( e ) {
+				if ( ! e.shiftKey ) {
+					return;
+				}
+				e.preventDefault();
+
+				self.preview.send( 'focus-widget-control', $( this ).prop( 'id' ) );
+			});
+		}
+	};
+
+	/**
+	 * Capture the instance of the Preview since it is private
+	 */
+	OldPreview = api.Preview;
+	api.Preview = OldPreview.extend( {
+		initialize: function( params, options ) {
+			api.WidgetCustomizerPreview.preview = this;
+			OldPreview.prototype.initialize.call( this, params, options );
+		}
+	} );
+
+	$(function () {
+		var settings = window._wpWidgetCustomizerPreviewSettings;
+		if ( ! settings ) {
+			return;
+		}
+
+		$.extend( api.WidgetCustomizerPreview, settings );
+
+		api.WidgetCustomizerPreview.init();
+	});
+
+})( window.wp, jQuery );