Advanced Constraints with constraintRows
<?xml version="1.0" encoding="utf-8"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute"> <mx:constraintRows> <mx:ConstraintRow id="row1" height="50%"/> <mx:ConstraintRow id="row2" height="50%"/> </mx:constraintRows> <mx:VBox top="row1:20" bottom="row1:20" horizontalCenter="0" width="50%" borderStyle="solid" backgroundColor="#666666"/> <mx:VBox top="row2:20" bottom="row2:20" horizontalCenter="0" width="50%" borderStyle="solid" backgroundColor="#999999"/> </mx:Application>