Flex 展开tree全部子节点

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
			   xmlns:s="library://ns.adobe.com/flex/spark"
			   xmlns:mx="library://ns.adobe.com/flex/mx">
	
	<fx:Declarations>
		
		<fx:XMLList id="treeData">
			<node label="Mail Box">
				<node label="Inbox">
					<node label="Marketing"/>
					<node label="Product Management"/>
					<node label="Personal"/>
				</node>
				
				<node label="Outbox">
					<node label="Professional"/>
					<node label="Personal"/>
				</node>
				
				<node label="Spam"/>
				<node label="Sent"/>
				
			</node>    
			
		</fx:XMLList>
		
	</fx:Declarations> 
	
	<fx:Script>
 
		<![CDATA[
			
			import mx.events.FlexEvent;  
			
			protected function tree_creationCompleteHandler(event:FlexEvent):void
			{
				// 必须要先进行验证
				tree.validateNow(); 
				
				// 展开所有tree上的节点
				for each(var item:XML in tree.dataProvider)
				{
					trace(item.toString());
					
					tree.expandChildrenOf(item,true);
				}
			} 
		]]>
		
	</fx:Script> 
	
	<mx:Tree id="tree" dataProvider="{treeData}" labelField="@label" x="0" y="0"
			 creationComplete="tree_creationCompleteHandler(event)" width="200"/> 
	
</s:Application>