anchor.diff:    /// changes that affects the matrix.
     void invalidateTransformMatrix() {
       _transformMatrix = null;
  +    _transformMatrixInverse = null;
       _invalidateToBoxTransformMatrix();
     }
   
  
positive.code:   double _rotation = 0.0;
  
    Matrix4 _transformMatrix = new Matrix4.identity();
    Matrix4 _transformMatrixNodeToBox;
    Matrix4 _transformMatrixBoxToNode;
  
  
negative.code:       return position;
      } else if (physicsParent is PhysicsGroup) {
        // Transform the position
        Vector4 parentPos = physicsParent._inverseMatrix().transform(new Vector4(position.x, position.y, 0.0, 1.0));
        Point newPos = new Point(parentPos.x, parentPos.y);
        return _positionToPhysics(newPos, physicsParent.parent);
      } else {
  