flex 20 Tree test

TreeTest.mxml
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
 <mx:XMLList id="treedata">
  <node label="javaCourse">
   <node label="teamA" data="select member">
    <node label="kim" data="☎ 268-4356"/>
    <node label="kang" data="☎ 345-0564"/>
    <node label="jung" data="☎ 567-9784"/>
   </node>
   <node label="teamB" data="select member">
    <node label="yoo" data="☎ 875-2345"/>
    <node label="shin" data="☎ 654-4563"/>
   </node>
  </node>
 </mx:XMLList>
 <mx:Panel width="300" height="200" layout="absolute" verticalCenter="0" horizontalCenter="0">
  <mx:HDividedBox x="0" y="0" width="280" height="160">
   <mx:Tree id="myTree" width="50%" height="100%" labelField="@label" showRoot="false" dataProvider="{treedata}" change="treeChanged(event)"/>
   <mx:TextArea height="100%" width="50%" text="{selectedNode.@data}"/>
  </mx:HDividedBox>
 </mx:Panel>
 <mx:Script>
  <![CDATA[
   import mx.controls.Alert;
   [Bindable]
   public var selectedNode:XML;
   
   // Event handler for the Tree control change event.
   public function treeChanged(event:Event):void{
   selectedNode = Tree(event.target).selectedItem as XML;
   }
  ]]>
 </mx:Script>
</mx:Application>