以下代码是示例代码，其中closeItem设置有坐标，menu也设置有坐标，这两坐标是啥关系？
auto closeItem = MenuItemImage::create(
“CloseNormal.png”,
“CloseSelected.png”,
CC_CALLBACK_1(HelloWorld::menuCloseCallback, this));
closeItem->setPosition(Point(origin.x + visibleSize.width - closeItem->getContentSize().width/2 ,
origin.y + closeItem->getContentSize().height/2));
// create menu, it's an autorelease object
auto menu = Menu::create(closeItem, NULL);
menu->setPosition(Point::ZERO);
this->addChild(menu, 1);