Flex拖拽-两个List之间拖拽

<?xml version="1.0" encoding="utf-8"?>
<mx:WindowedApplication xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" creationComplete="creationHandler();">
	<mx:Script>
		<![CDATA[
		import mx.events.DragEvent;
		import mx.collections.ArrayCollection;
		[Bindable]
		public var isEnabled:Boolean = true;
		private static const DIS_LABEL:String = "不能拖拽";
		private static const EN_LABEL:String = "可以拖拽"; 
		private function creationHandler():void {
			list1.dataProvider = new ArrayCollection(['Spider Monkey', 'Orangutan', 'Gorilla']);
			list2.dataProvider = new ArrayCollection(['Lion', 'Cheetah', 'Puma'])
		}
		private function clickHandler():void {
			enableBtn.label = ( enableBtn.label == DIS_LABEL ) ? EN_LABEL : DIS_LABEL;
			isEnabled = !isEnabled;
		}
		private function dragEnterHandler( evt:DragEvent ):void {
			evt.target.dropEnabled = ( evt.target != evt.dragInitiator );
		}
		]]>
		</mx:Script>
		<mx:VBox width="100%" height="100%">
			<mx:Button id="enableBtn" label="{EN_LABEL}" click="clickHandler();"/>
			<mx:HBox width="100%" height="100%">
				<mx:List id="list1" width="200" height="200" dragEnabled="{isEnabled}" dragMoveEnabled="true" dragEnter="dragEnterHandler(event);"/>
				<mx:List id="list2" width="200" height="200" dragEnabled="{isEnabled}" dragMoveEnabled="true" dragEnter="dragEnterHandler(event);"/>
			</mx:HBox>
		</mx:VBox>
</mx:WindowedApplication>