如何使用Flex PopUpMenuButton

<?xml version="1.0" encoding="utf-8"?>
<!-- PopUpMenuButton control example. -->
<!--
	如何使用Flex PopUpMenuButton
	MyShareBook.cn 翻译
-->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">

    <mx:Script>
        <![CDATA[
            import mx.events.*;
            import mx.controls.*;
			
            //Event handler, invoked when you select from the menu.
            public function itemClickHandler(event:MenuEvent):void {
                Alert.show("Menu label: " + event.label
                    + "  \n menu item index within parent menu: " + event.index);
            }
        ]]>
    </mx:Script>
	
    <!-- A an data provider in E4X format. -->
    <mx:XMLList id="treeDP2">
        <node label="Inbox"/>
        <node label="Calendar"/>
        <node label="Deleted Items"/>
    </mx:XMLList>

    <mx:Panel title="PopUpMenuButton Control Example" height="100%" width="100%" 
        paddingTop="10" paddingLeft="10" paddingRight="10">

		<mx:Label width="100%" color="blue"
		    text="Click the down arrow to open the menu."/>

        <mx:PopUpMenuButton id="p2" 
            dataProvider="{treeDP2}" 
            labelField="@label"
            itemClick="itemClickHandler(event);"/>

	</mx:Panel>
</mx:Application>