Index: wp-includes/js/jquery/ui/draggable.js
===================================================================
--- wp-includes/js/jquery/ui/draggable.js	(revision 31176)
+++ wp-includes/js/jquery/ui/draggable.js	(working copy)
@@ -766,6 +766,9 @@
 		});
 	},
 	drag: function( event, ui, draggable ) {
+
+		var that = this;
+
 		$.each( draggable.sortables, function() {
 			var innermostIntersecting = false,
 				sortable = this;
@@ -799,11 +802,11 @@
 				// so that the move-in stuff gets fired only once.
 				if ( !sortable.isOver ) {
 					sortable.isOver = 1;
+					//Now we fake the start of dragging for the sortable instance,
+					//by cloning the list group item, appending it to the sortable and using it as draggable.currentItem
+					//We can then fire the start event of the sortable with our passed browser event, and our own helper (so it doesn't create a new one)
+					sortable.currentItem = $(that).clone().removeAttr("id").appendTo(sortable.element).data("ui-sortable-item", true);
 
-					sortable.currentItem = ui.helper
-						.appendTo( sortable.element )
-						.data( "ui-sortable-item", true );
-
 					// Store helper option to later restore it
 					sortable.options._helper = sortable.options.helper;
 
@@ -872,6 +875,8 @@
 					sortable.options.revert = sortable.options._revert;
 					sortable.options.helper = sortable.options._helper;
 
+					//Now we remove our currentItem, the list group clone again, and the placeholder, and animate the helper back to it's original size
+					sortable.currentItem.remove();
 					if ( sortable.placeholder ) {
 						sortable.placeholder.remove();
 					}