Stage property of Application and all its component

Sorry it is a little bit about flex but I have nowhere to ask. so.

<?xml version="1.0"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
                creationComplete="initApp()">

    <mx:Script>
        <![CDATA[
            public function initApp():void
            {
                txt.text += txt.stage;
                txt.text += stage;
                //result is nullnull
            }
        ]]>
    </mx:Script>
<mx:Text id="txt"/>
</mx:Application>

not only the components added on Application and all kind of DisplayObject added in a UIComponent cannot access their stage property. which make me cannot use KeyboardEvent.

Please help please :frowning: