[flexcoders] PopUpButton not instantiating it's UI component untill calling open()

[alex]

I'm putting for example bunch of radioButtons in the popUp component. The label 
of PopUpButton is to be set from the default selection of RadioButtonGroup , 
the problem is all the properties of RadioGroup like the number of children or 
selection value are null and only until I open the popUpButton they get 
instantiated !
The fix is on the creationComplete of PopUpButton to open and close it ! But 
it's annoying because it might leave some visual artifacts ( may be in future) 
Anyone encountered this problem ?


<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"; layout="absolute" 
creationPolicy="all">
             <mx:PopUpButton id="picker"  label="{rdg.selectedValue}"    >
                <mx:popUp>
                       <mx:Box id="pickerBox" creationPolicy="all">
                             <mx:RadioButtonGroup id="rdg" />
                             <mx:RadioButton groupName="rdg" value="countA"     
label="A" selected="true"/>
                             <mx:RadioButton groupName="rdg" value="count_B" 
label="B"/>
                             <mx:RadioButton groupName="rdg" value="count_C" 
label="C"/>
                             <mx:RadioButton groupName="rdg" value="count_D" 
label="D"/>
                       </mx:Box>
               </mx:popUp>
             </mx:PopUpButton>
</mx:Application>