Using various Alpha properties
<?xml version="1.0" encoding="utf-8"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" backgroundColor="0xFFFFFF"> <mx:Panel alpha="0.80" borderColor="#33ff99" borderAlpha="0.37" backgroundAlpha="0.29" backgroundColor="#ff0000"> <mx:Label text="Label" /> <mx:Text text="Some Text" /> </mx:Panel> </mx:Application>