Displaying a Tree control as a pop up for a Flex PopUpButton control

The following example shows how you can use a Tree control as a PopUpButton control’s pop up in Flex

<? xml version="1.0" encoding="utf-8" ?>
<!--  http://blog.flexexamples.com/2008/02/26/displaying-a-tree-control-as-a-pop-up-for-a-flex-popupbutton-control/  -->
< mx:Application  xmlns:mx ="http://www.adobe.com/2006/mxml"
        layout ="vertical"
        verticalAlign ="middle"
        backgroundColor ="white" >

     < mx:Style >
        Tree {
            textAlign: left;
            fontWeight: normal;
        }
     </ mx:Style >

     < mx:XML  id ="mlb"  source ="mlb.xml"   />

     < mx:ApplicationControlBar  dock ="true" >
         < mx:PopUpButton  label ="Please select a team" >
             < mx:popUp >
                 < mx:Tree  id ="tree"
                        dataProvider ="{mlb}"
                        labelField ="@label"
                        showRoot ="false"
                        width ="200"
                        rowCount ="8"   />
             </ mx:popUp >
         </ mx:PopUpButton >
     </ mx:ApplicationControlBar >

</ mx:Application >