[]scrollRect 改变后子对象的鼠标事件失效

bg=new Laya.Sprite();
Laya.stage.addChild(bg);
bg.size(800,600);
bg.loadImage("aa_1.Png",0,0,800,600);

poly=new Laya.Sprite();
bg.addChild(poly);
poly.size(36,36);
poly.pivot(18,18);
poly.loadImage("SafeExitL.png",0,0,36,36);
poly.pos(400,300);

poly.on("mousedown", this, polyonMouseDown);

bg.scrollRect=new Laya.Rectangle(100,100,700,500);
bg.scale(1.5,1.5);
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加上这句bg.scrollRect=new Laya.Rectangle(100,100,700,500); 子对象的鼠标事件失效了