Use SetProperty to change panel property value
<?xml version="1.0"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"> <mx:states> <mx:State name="Register"> <mx:SetProperty target="{loginPanel}" name="title" value="Register" /> <mx:SetStyle target="{loginPanel}" name="backgroundColor" value="0x00FFFF" /> <mx:SetProperty target="{loginButton}" name="label" value="Register" /> <mx:SetStyle target="{loginButton}" name="color" value="0xFFFF00" /> </mx:State> </mx:states> <mx:Panel id="loginPanel" title="Login" horizontalScrollPolicy="off" verticalScrollPolicy="off"> <mx:Form id="loginForm"> <mx:Button label="Login" id="loginButton" /> </mx:Form> <mx:ControlBar width="100%"> <mx:Button label="Change State" click="currentState = currentState=='Register' ? '':'Register';" /> </mx:ControlBar> </mx:Panel> </mx:Application>