Flex4 how to select a menu item in menu bar

I have a menu bar in a spark Panel, I want to select one of the menu items by using Actionscript I don't know how to target one of the items. Here is an extract from my component code.

<?xml version="1.0" encoding="utf-8"?>

<s:layout>
    <s:BasicLayout />
&l开发者_运维知识库t;/s:layout>
<fx:Script>
    <![CDATA[
        import events.CustomMenuEvent;

        import mx.collections.ArrayCollection;
        import mx.events.MenuEvent;

        public function update(id:String):void
        {
            // This is where I would call the menu to update the button
                            // from its mediator.
        }

        protected function appMenu_itemClickHandler(event:MenuEvent):void
        {
            var data:String = event.item.@data;
            var menuEvent:CustomMenuEvent = new CustomMenuEvent(CustomMenuEvent.ITEM_CLICKED);
            menuEvent.toggled = Boolean(event.item.@toggled == "true");
            menuEvent.data = data;
            dispatchEvent(menuEvent);
        }
    ]]>
</fx:Script>

<fx:Declarations>
    <fx:XMLList id="menuXML">
        <fx:menuitem label="File">
            <fx:menuitem label="Open" data="open"/>
            <fx:menuitem label="Exit" data="exit"/>
        </fx:menuitem>
        <fx:menuitem label="View">
            <fx:menuitem label="Map" type="check" data="map"/>
            <fx:menuitem label="Flights" type="check" data="flights"/>
            <fx:menuitem label="Altitude Graph" type="check" data="altitude"/>
        </fx:menuitem>
    </fx:XMLList>
</fx:Declarations>

<s:controlBarContent>
    <mx:MenuBar id="appMenu" 
                labelField="@label" 
                showRoot="true"
                dataProvider="{menuXML}"
                itemClick="appMenu_itemClickHandler(event)"/>
</s:controlBarContent>

Ok I found this post which pretty much does what I want.

Programatically enable/disable menuBar buttons in Flex 4