anchor.diff:    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);
  +
  +  // tester.checkFrame();
   }
   
  +final bool debugDisplayList = false; // set this to true to use the test rendering logic
  +
   void main() {
  +  // 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, or in case we
  +  // want a renderViewOverride.
  +  UINodeAppView.initUINodeAppView(renderViewOverride: debugDisplayList ? tester : null);
  +
     RenderFlex flexRoot = new RenderFlex(direction: FlexDirection.vertical);
   
     RenderProxyBox proxy = new RenderProxyBox();
  
positive.code: import 'package:vector_math/vector_math.dart';
  
  import '../lib/solid_color_box.dart';
  
  // Solid colour, RenderObject version
  void addFlexChildSolidColor(RenderFlex parent, sky.Color backgroundColor, { int flex: 0 }) {
  
negative.code:   transformBox = new RenderTransform(child: flexRoot, transform: new Matrix4.identity());
    RenderPadding root = new RenderPadding(padding: new EdgeDims.all(20.0), child: transformBox);
  
    UINodeAppView.appView.root = root;
    addPersistentFrameCallback(rotate);
  }
  