anchor.diff:          ..textBaseline = "top"
           ..font = '12px Verdana';
       } else {
  -      (ctx as RenderingContext)
  -//                               ..enable(RenderingContext.DEPTH_TEST);
  +      if (depthTest) {
  +        (ctx as RenderingContext).enable(RenderingContext.DEPTH_TEST);
  +      }
  +      if (blending) {
  +        (ctx as RenderingContext)
  +          ..enable(BLEND)
  +          ..blendFunc(SRC_ALPHA, ONE_MINUS_SRC_ALPHA);
  +      }
  +//      (ctx as RenderingContext)
   //                               ..enable(RenderingContext.POLYGON_OFFSET_FILL);
  -            ..enable(BLEND)
  -            ..blendFunc(SRC_ALPHA, ONE_MINUS_SRC_ALPHA)
   //                               ..polygonOffset(1.0, 1.0);
  -          ;
  +      ;
       }
       canvas.onFullscreenChange.listen(_handleFullscreen);
       world = createWorld();
  
positive.code:   void start() {
      _init().then((_) {
        _lastTimeP = window.performance.now();
  //      physicsLoop();
        window.requestAnimationFrame(_firstUpdate);
      });
    }
  
negative.code:   GameBase(String appName, String canvasSelector, int width, int height,
        {this.spriteSheetName: 'assets',
        this.bodyDefsName: 'assets',
        bool webgl: false,
        bool depthTest: true,
        bool blending: true})
        : canvas = querySelector(canvasSelector),
          helper = new GameHelper(appName),
          webgl = webgl,
  