Stack Overflow: Click event outside MovieClip in AS3

/**
 * Copyright Mattias ( http://wonderfl.net/user/Mattias )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/eFao
 */

package
{
    import flash.display.Sprite;
    import flash.events.MouseEvent;
    
    public class FlashTest extends Sprite
    {
        
        private var _menu : Sprite;
        
        public function FlashTest()
        {
            _menu = new Sprite();
            _menu.x = 100;
            _menu.y = 100;
            _menu.alpha = 0.5;
            
            with(_menu.graphics)
            {
                beginFill(0xFF0000, 1);
                drawRect(0, 0, 300, 300);
                endFill();
            }
            
            addChild(_menu);
            
            _menu.addEventListener(MouseEvent.CLICK, onClickHandler);
            stage.addEventListener(MouseEvent.CLICK, onClickHandler);

        }
        
        private function onClickHandler(event : MouseEvent) : void
        {
            switch(event.target)
            {
                case _menu:
                    _menu.alpha = 0.5;
                    break;
                    
                case stage:
                    _menu.alpha = 1;
                    break;
            }

        }
        
    }

}