var a_mc:MovieClip=new a_mc_();
var b_mc:MovieClip=new b_mc_();

addChild(a_mc);
a_mc.x=30;
a_mc.y=30;

addChild(b_mc);
b_mc.x=80;
b_mc.y=80;

b_mc.addEventListener(MouseEvent.MOUSE_DOWN,xstartmove);
function xstartmove(evt:MouseEvent):void {
	b_mc.removeEventListener(MouseEvent.MOUSE_DOWN,xstartmove);

	setChildIndex(b_mc,numChildren-1);//優先を上にする
	b_mc.x=mouseX;
	b_mc.y=mouseY;

	stage.addEventListener(MouseEvent.MOUSE_MOVE,xmoveing);
	function xmoveing(evt:MouseEvent):void {
		b_mc.x=mouseX;
		b_mc.y=mouseY;
		evt.updateAfterEvent();//滑らか移動
	}

	b_mc.addEventListener(MouseEvent.MOUSE_DOWN,xstopmove);
	function xstopmove(evt:Event):void {
		b_mc.removeEventListener(MouseEvent.MOUSE_DOWN,xstopmove);

		if (b_mc.hitTestObject(a_mc)) {
			trace("当たった");
			removeChild(a_mc);
		}

		stage.removeEventListener(MouseEvent.MOUSE_MOVE,xmoveing);
		b_mc.addEventListener(MouseEvent.MOUSE_DOWN,xstartmove);//再び移動できるようにする
	}
}