anchor.diff:      } else {
         _gl.bindFramebuffer(WEBGL.FRAMEBUFFER, _framebuffer.framebuffer);
       }
  -    _gl.viewport(0, 0, _perspective.width, _perspective.height);
  +    _gl.viewport(viewPortX, viewPortY, _perspective.width, _perspective.height);
   
       if (clearColorBuffer || clearDepthBuffer) {
         int mode = 0;
  
positive.code:   //final VM.Matrix4 _pMatrix = new VM.Matrix4.identity();
    bool clearColorBuffer = true;
    bool clearDepthBuffer = true;
    List<DrawStats> stats = null;
    final Camera _camera;
    final Perspective _perspective;
  
negative.code:     _lastFov_ = fov;
      //LogInfo(
      //    "New perspective: ${perspar.width} ${perspar.height} ${perspar.fov}");
      UpdatePerspective();
    }
  
    void Adjust(HTML.CanvasElement canvas) {
  