anchor.diff:    bool contains(Vector p) => HitTest.contains(getWorldShape(), p);
     
     void update(num dt) { }
  +  void draw() { drawDefault(); }
   }
   
   class System extends SafeListItem {
  
positive.code:   bool _destroyed = false;
    bool get destroyed => _destroyed;
    
    Actor({Vector position, num rotation, num depth, T shape, Sprite sprite}) {
      if (position != null) this.position = new Vector.from(position);
      else this.position = Vector.zero;
  
negative.code:     else pencil.clear();
      for (Actor actor in actors) {
        if (!actor.visible) continue;
        actor._drawn = true;
        actor.draw();
        if (!actor._drawn) {
          if (actor.sprite != null) pencil.move(actor.position.x, actor.position.y).rotate(actor.rotation).sprite(actor.sprite).draw();
          if (actor.shape != null) pencil.move(actor.position.x, actor.position.y).rotate(actor.rotation).shape(actor.shape).draw();
        }
        if (debug) {
          Shape debugShape = (actor.shape ?? actor.sprite?.getBounds());
          if (debugShape is Label) debugShape = null;
  