Using the itemDoubleClick event to open nodes in a Flex Tree control

<? xml version="1.0" encoding="utf-8" ?>
<!--  http://blog.flexexamples.com/2007/11/29/using-the-itemdoubleclick-event-to-open-nodes-in-a-flex-tree-control/  -->
< mx:Application  xmlns:mx ="http://www.adobe.com/2006/mxml"
        layout ="horizontal"
        verticalAlign ="middle"
        backgroundColor ="white"
        creationComplete ="init();" >

     < mx:Script >
         <![CDATA[
            import mx.events.ListEvent;

            private function tree_itemDoubleClick(evt:ListEvent):void {
                var node:XML = tree.selectedItem as XML;
                var isOpen:Boolean = tree.isItemOpen(node);
                tree.expandItem(node, !isOpen);
            }
         ]]>
     </ mx:Script >

     < mx:XMLListCollection  id ="xmlListColl" >
         < mx:source >
             < mx:XMLList >
                 < node  label ="One" >
                     < node  label ="One.1" >
                         < node  label ="One.1.1" >
                             < node  label ="One.1.1.1" >
                                 < node  label ="One.1.1.1.1"   />
                             </ node >
                         </ node >
                     </ node >
                     < node  label ="One.2"   />
                     < node  label ="One.3"   />
                 </ node >
                 < node  label ="Two" >
                     < node  label ="Two.1"   />
                     < node  label ="Two.2"   />
                     < node  label ="Two.3"   />
                 </ node >
                 < node  label ="Three"   />
             </ mx:XMLList >
         </ mx:source >
     </ mx:XMLListCollection >

     < mx:ApplicationControlBar  dock ="true" >
         < mx:CheckBox  id ="checkBox"
                label ="doubleClickEnabled:"
                labelPlacement ="left"
                selected ="true"   />
     </ mx:ApplicationControlBar >

     < mx:Tree  id ="tree"
            dataProvider ="{xmlListColl}"
            labelField ="@label"
            width ="250"
            rowCount ="6"
            doubleClickEnabled ="{checkBox.selected}"
            itemDoubleClick ="tree_itemDoubleClick(event);"
            showScrollTips ="true"   />

</ mx:Application >