flex4 自定义右键菜单

1. <?xml version="1.0" encoding="utf-8"?>  
   <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"  
           layout="vertical"  
           verticalAlign="middle"  
           backgroundColor="white"  
           creationComplete="init()">  
      
       <mx:Script>  
           <![CDATA[ 
               import mx.controls.Alert; 
     
               [Bindable] 
               private var cm:ContextMenu; 
     
               private var alert:Alert; 
     
               private function init():void { 
                   var cmi:ContextMenuItem = new ContextMenuItem("菜单项",true); 
                   cmi.addEventListener(ContextMenuEvent.MENU_ITEM_SELECT,contextMenuItem_menuItemSelect); 
                   var cmi1:ContextMenuItem = new ContextMenuItem("菜单项1",false); 
                   cmi1.addEventListener(ContextMenuEvent.MENU_ITEM_SELECT,contextMenuItem_menuItemSelect1); 
                    
                   cm = new ContextMenu(); 
                   cm.hideBuiltinitems(); 
                   cm.customItems = [cmi,cmi1]; 
                   cm.addEventListener(ContextMenuEvent.MENU_SELECT,contextMenu_menuSelect); 
               } 
     
               private function contextMenu_menuSelect(evt:ContextMenuEvent):void { 
                   dataGrid.selectedindex = lastRolloverIndex; 
               } 
     
               private function contextMenuItem_menuItemSelect(evt:ContextMenuEvent):void { 
                   var obj:Object = dataGrid.selectedItem; 
                   alert = Alert.show("Property A: " + obj.@propertyA + "\n" + "Property B: " + obj.@propertyB,obj.@label,Alert.OK); 
               } 
               private function contextMenuItem_menuItemSelect1(evt:ContextMenuEvent):void { 
                   var obj:Object = dataGrid.selectedItem; 
                   alert = Alert.show("Property A: " + obj.@propertyA + "\n" + "Property B: " + obj.@propertyB,Alert.OK); 
               } 
           ]]>  
       </mx:Script>  
      
       <mx:XML id="itemsXML">  
           <items>  
               <item label="Item 1" data="i001" propertyA="Item 1.A" propertyB="Item 1.B" />  
               <item label="Item 2" data="i002" propertyA="Item 2.A" propertyB="Item 2.B" />  
               <item label="Item 3" data="i003" propertyA="Item 3.A" propertyB="Item 3.B" />  
               <item label="Item 4" data="i004" propertyA="Item 4.A" propertyB="Item 4.B" />  
               <item label="Item 5" data="i005" propertyA="Item 5.A" propertyB="Item 5.B" />  
               <item label="Item 6" data="i006" propertyA="Item 6.A" propertyB="Item 6.B" />  
               <item label="Item 7" data="i007" propertyA="Item 7.A" propertyB="Item 7.B" />  
               <item label="Item 8" data="i008" propertyA="Item 8.A" propertyB="Item 8.B" />  
           </items>  
       </mx:XML>  
      
       <mx:Number id="lastRolloverIndex" />  
      
       <mx:DataGrid id="dataGrid"  
               width="400"  
               dataProvider="{itemsXML.item}"  
                contextMenu="{cm}"  
                itemRollover="lastRolloverIndex = event.rowIndex">  
           <mx:columns>  
               <mx:DataGridColumn id="labelCol"  
                       datafield="@label"  
                       headerText="Label:" />  
      
               <mx:DataGridColumn id="propACol"  
                       datafield="@propertyA"  
                       headerText="Property A:" />  
      
               <mx:DataGridColumn id="propBCol"  
                       datafield="@propertyB"  
                       headerText="Property B:" />  
           </mx:columns>  
       </mx:DataGrid>  
      
       <mx:Label text="{dataGrid.selectedItem.@label}" />  
      
   </mx:Application>