anchor.diff:    transformBox = new RenderTransform(child: flexRoot, transform: new Matrix4.identity());
     RenderPadding root = new RenderPadding(padding: new EdgeDims.all(20.0), child: transformBox);
   
  -  // Because we're going to use UINodes, we want to initialise its
  -  // AppView, not use the default one. We don't really need to do
  -  // this, because RenderObjectToUINodeAdapter does it for us, but
  -  // it's good practice in case we happen to not have a
  -  // RenderObjectToUINodeAdapter in our tree at startup.
  -  UINodeAppView.initUINodeAppView();
     UINodeAppView.appView.root = root;
  -
     addPersistentFrameCallback(rotate);
   }
  
positive.code:   transformBox.translate(transformBox.size.width / 2.0, transformBox.size.height / 2.0);
    transformBox.rotateZ(delta);
    transformBox.translate(-transformBox.size.width / 2.0, -transformBox.size.height / 2.0);
  }
  
  void main() {
    RenderFlex flexRoot = new RenderFlex(direction: FlexDirection.vertical);
  
    RenderProxyBox proxy = new RenderProxyBox();
  
negative.code: double timeBase;
  RenderTransform transformBox;
  
  final TestRenderView tester = new TestRenderView();
  
  void rotate(double timeStamp) {
    if (timeBase == null)
      timeBase = timeStamp;
  