Index: wp-admin/js/widgets.dev.js
===================================================================
--- wp-admin/js/widgets.dev.js	(revision 16267)
+++ wp-admin/js/widgets.dev.js	(working copy)
@@ -2,19 +2,24 @@
 (function($) {
 
 wpWidgets = {
+	
+	toggleHolder : function(widgetHolder) {
+		var c = $(widgetHolder).siblings('.widgets-sortables'), p = $(widgetHolder).parent();
+		if ( !p.hasClass('closed') ) {
+			c.sortable('disable');
+			p.addClass('closed');
+		} else {
+			p.removeClass('closed');
+			c.sortable('enable').sortable('refresh');
+		}
+	},
 
 	init : function() {
+
 		var rem, sidebars = $('div.widgets-sortables');
 
 		$('#widgets-right').children('.widgets-holder-wrap').children('.sidebar-name').click(function(){
-			var c = $(this).siblings('.widgets-sortables'), p = $(this).parent();
-			if ( !p.hasClass('closed') ) {
-				c.sortable('disable');
-				p.addClass('closed');
-			} else {
-				p.removeClass('closed');
-				c.sortable('enable').sortable('refresh');
-			}
+			wpWidgets.toggleHolder($(this));
 		});
 
 		$('#widgets-left').children('.widgets-holder-wrap').children('.sidebar-name').click(function() {
@@ -86,7 +91,9 @@
 				wpWidgets.fixWebkit();
 			}
 		});
-
+		
+		var openedHolders = new Array();
+	
 		sidebars.sortable({
 			placeholder: 'widget-placeholder',
 			items: '> .widget',
@@ -98,8 +105,30 @@
 				wpWidgets.fixWebkit(1);
 				ui.item.children('.widget-inside').hide();
 				ui.item.css({'marginLeft':'','width':''});
+				$('#widgets-right .sidebar-name')
+				.hover(function(){
+					// Open only those that are closed
+					if ( $(this).parent().hasClass('closed') )
+					{
+						openedHolders.push( $(this) );		// Remember this holder
+						wpWidgets.toggleHolder( $(this) );	// Now open it
+					}
+				},
+				function(){
+				}
+				);
 			},
 			stop: function(e,ui) {
+				// No more reacting to mouse hovers.
+				$('#widgets-right .sidebar-name').unbind('mouseenter');
+				$('#widgets-right .sidebar-name').unbind('mouseleave');
+				// Close all holders opened by hovering.
+				for(counter = 0; counter < openedHolders.length; counter++)
+				{
+					wpWidgets.toggleHolder( openedHolders[counter] );
+				}
+				openedHolders = new Array();
+				
 				if ( ui.item.hasClass('ui-draggable') && ui.item.data('draggable') )
 					ui.item.draggable('destroy');