Use Slider to control the width and height of ConstraintColumn
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"> <mx:Script> [Bindable] public var txt:String = "Cor"; private function changeColumnProportion():void { this.leftCol.percentWidth = (10 * colSlider.value); } private function changeRowProportion():void { this.row1.percentHeight = (10 * rowSlider.value); } </mx:Script> <mx:Canvas width="100%" height="100%" horizontalScrollPolicy="off" verticalScrollPolicy="off"> <mx:constraintColumns> <mx:ConstraintColumn id="leftCol" width="50%" /> <mx:ConstraintColumn id="rightCol" width="50%" /> </mx:constraintColumns> <mx:constraintRows> <mx:ConstraintRow id="row1" height="20%"/> <mx:ConstraintRow id="row2" height="80%" /> </mx:constraintRows> <mx:HSlider id="colSlider" change="changeColumnProportion()" value="5"/> <mx:HSlider id="rowSlider" x="200" change="changeRowProportion()" value="5"/> <mx:Label text="{txt}" left="leftCol:0" right="leftCol:0" top="row2:0" bottom="row2:0"/> <mx:Label text="{txt}" left="rightCol:0" right="rightCol:0" top="row2:0" bottom="row2:0"/> </mx:Canvas> </mx:Application>