anchor.diff:  
     void handleEvent(sky.Event event) {
       if (event.type == 'pointerdown')
  -      decoration = new BoxDecoration(backgroundColor: const sky.Color(0xFFFF0000));
  +      decoration = new BoxDecoration(backgroundColor: const Color(0xFFFF0000));
       else if (event.type == 'pointerup')
         decoration = new BoxDecoration(backgroundColor: backgroundColor);
     }
  
positive.code: }
  
  class RenderSolidColor extends RenderDecoratedSector {
    RenderSolidColor(sky.Color backgroundColor, {
      this.desiredDeltaRadius: double.INFINITY,
      this.desiredDeltaTheta: kTwoPi
    }) : this.backgroundColor = backgroundColor,
  
negative.code: 
    double desiredDeltaRadius;
    double desiredDeltaTheta;
    final Color backgroundColor;
  
    SectorDimensions getIntrinsicDimensions(SectorConstraints constraints, double radius) {
      return new SectorDimensions.withConstraints(constraints, deltaTheta: 1.0); // 1.0 radians
  