Put TextArea and Button into VBox
<?xml version="1.0"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"> <mx:Panel title="My Application" paddingTop="10" paddingBottom="10" paddingLeft="10" paddingRight="10"> <mx:HBox> <mx:TabNavigator borderStyle="solid"> <mx:VBox label="Pane1" width="300" height="150"> <mx:TextArea text="Hello World" /> <mx:Button label="Submit" /> </mx:VBox> <mx:VBox label="Pane2" width="300" height="150"> </mx:VBox> </mx:TabNavigator> </mx:HBox> </mx:Panel> </mx:Application>