Fix mouse event propagation in IE

Nested sortables were breaking.  Dragging an inner sortable item would also drag the outer item.  This is due to IE not persisting the state of event.originalEvent.mouseHandled.

Author: Adam McCrea

ui/jquery.ui.mouse.js

@@ -12,6 +12,12 @@
  */
 (function( $, undefined ) {
 
+var mouseHandled = false;
+
+$(document).mousedown(function(e) {
+  mouseHandled = false;  
+})
+
 $.widget("ui.mouse", {
 	options: {
 		cancel: ':input,option',
@@ -44,9 +50,7 @@ $.widget("ui.mouse", {
 
 	_mouseDown: function(event) {
 		// don't let more than one widget handle mouseStart
-		// TODO: figure out why we have to use originalEvent
-		event.originalEvent = event.originalEvent || {};
-		if (event.originalEvent.mouseHandled) { return; }
+		if (mouseHandled) { return; }
 
 		// we may have missed mouseup (out of window)
 		(this._mouseStarted && this._mouseUp(event));
@@ -91,7 +95,7 @@ $.widget("ui.mouse", {
 		// anymore, so this fix is needed
 		($.browser.safari || event.preventDefault());
 
-		event.originalEvent.mouseHandled = true;
+		mouseHandled = true;
 		return true;
 	},