xmlns:mx="library://ns.adobe.com/flex/mx"
xmlns:s="library://ns.adobe.com/flex/spark"
creationComplete="initApp();">
import mx.controls.Alert;
private function initApp():void {
b1.addEventListener(MouseEvent.CLICK, myEventHandler);
}
private function myEventHandler(event:Event):void {
Alert.show("An event occurred.");
}