Index: src/wp-admin/js/widgets.js
===================================================================
--- src/wp-admin/js/widgets.js	(revision 32454)
+++ src/wp-admin/js/widgets.js	(working copy)
@@ -113,6 +113,8 @@
 			}
 		});
 
+		var widgetHoverTimeout;
+
 		sidebars.sortable({
 			placeholder: 'widget-placeholder',
 			items: '> .widget',
@@ -120,6 +122,9 @@
 			cursor: 'move',
 			distance: 2,
 			containment: 'document',
+			out : function( event, ui ) {
+				clearTimeout( widgetHoverTimeout );
+			},
 			start: function( event, ui ) {
 				var height, $this = $(this),
 					$wrap = $this.parent(),
@@ -135,6 +140,10 @@
 					// Prevents jumping when dragging a widget from an open sidebar to a closed sidebar below.
 					height = ui.item.hasClass('ui-draggable') ? $this.height() : 1 + $this.height();
 					$this.css( 'min-height', height + 'px' );
+				} else {
+					widgetHoverTimeout = setTimeout( function() {
+						$wrap.removeClass('closed');
+					}, 300 );
 				}
 			},