class MenuBar extends MovieClip
{
    public function MenuBar()
    {
        btn = new Button();
        btn.label = "home";
        btn.addEventListener('click', onClick);
    }
    private function onClick(event:MouseEvent)
    {
        dispatchEvent(event);
    }
}
//-----------------------------------------------------
var menu = new MenuBar()
menu.addEventListener('click', onClick)
function onClick(event:Event)
{
    trace(event.currentTarget.label);//home
}