anchor.diff:      drawOverride(ctx);
     }
   
  -  bool _isClipped(AffineTransform tx, CanvasRenderingContext2D ctx){
  -    if(clip){
  -      // a lot more impl to do here...
  -    }
  -    return false;
  -  }
  -
     void _invalidateParent(){
       assert(this._parent != null);
       _invalidatedEventHandle.fireEvent(EventArgs.empty);
  
positive.code:   num _width, _height, _alpha = 1;
    bool _cacheEnabled = false;
    Size _lastDrawSize;
    bool clip = false;
    ThingParent _parent;
  
    Thing(this._width, this._height);
  
negative.code: 
  // TODO: 'alpha' does not compose well. If a parent is 50% and the child is
  //       50% the render should be at %25, right? :-/
  // TODO: support clipping - https://github.com/kevmoo/bot.dart/issues/15
  
  abstract class Thing extends AttachableObject {
    final List<AffineTransform> _transforms = new List<AffineTransform>();
  