docs: function MenuItemSprite (opts) {
      MenuItemSprite.superclass.constructor.call(this, opts)
  
      var normalImage   = opts.normalImage,
          selectedImage = opts.selectedImage,
          disabledImage = opts.disabledImage
  
      this.normalImage = normalImage
      this.selectedImage = selectedImage
      this.disabledImage = disabledImage
  
      this.contentSize = normalImage.contentSize
  }