anchor.diff:  
     Rect _visibleArea;
   
  -  Rect get visibleArea => _visibleArea;
  +  Rect get visibleArea {
  +    if (_visibleArea == null) _calcTransformMatrix();
  +    return _visibleArea;
  +  }
   
     // Setup
   
  
positive.code: 
      // Add new references
      _addSpriteBoxReference(_rootNode);
    }
  
    // Tracking of frame rate and updates
  
negative.code:     _transformMode = value;
  
      // Invalidate stuff
      markNeedsLayout();
    }
  
    /// The transform mode used by the [SpriteBox].
  