public function constructor()

{

    btn.addEventListener(MouseEvent.MOUSE_OVER, over);

    btn.addEventListener(MouseEvent.MOUSE_OUT, out);

}

 

private function over(event:MouseEvent)

{

    stage.addEventListener(Event.ENTER_FRAME, alphaPlus);

}

 

private function alphaPlus(event:Event)

{

    btn.mc.alpha += 0.1; //Изменяем значение alpha, изначально равное 0.

}

 

private function out(event:MouseEvent)

{

    stage.removeEventListener(Event.ENTER_FRAME, alphaPlus)

}