[flexcoders] how to use stage in mxml

[markflex2007]

I try to get current stage size with the code,but I get error
"TypeError: Error #1009: Cannot access a property or method of a null object 
reference.".
It seems I get error for stage.height.

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"; layout="absolute"  
           creationPolicy="all" resize="resizeHandler(event)">
<mx:Script>
        <![CDATA[
                import mx.events.ResizeEvent;
                 
                
                private function resizeHandler(event:ResizeEvent):void{
                
                   
                   trace("height:" + stage.height);
                   trace("height:" + stage.width);
                    
                }
        ]]>
</mx:Script>

...
...
         
</mx:Application>


Please help me.Thanks

Mark