flex树形选择用户的实现

使用flex tree 和list实现如下选择用户的效果
<?xml version="1.0" encoding="utf-8"?>
<mx:TitleWindow xmlns:mx="http://www.adobe.com/2006/mxml" layout="vertical"
                showCloseButton="true" creationComplete="loadMenu()"
                close="closeWindow()" styleName="customPopUp"  width="608" height="482"
                horizontalAlign="center" title="选择系统用户：">
    <mx:Style source="./css/cssblue.css"/>
    <mx:Script>
<![CDATA[
        import comas.base.common.Globa;
        import mx.controls.Alert;
        import mx.managers.PopUpManager;
        import comas.base.common.HttpUtil;
        import mx.rpc.events.ResultEvent;
        import mx.utils.StringUtil;
        import mx.events.ToolTipEvent;
        import mx.controls.ToolTip;
        import mx.events.ValidationResultEvent;
        import mx.collections.ArrayCollection;
        [Bindable]
        public var returnFunction:Function;
        public var tracerObject:Object;
        public var initUsers:String;
      
        private function doSubmit():void
        {