private void ResizeMe()
        {
            // Tree or scale changed. Update control size to fit.

            if (_boxen == null)
            {
                return;
            }
            var newSize = _boxen.getBounds();

            // NOTE side-effect: control is invalidated from resize BUG except when size doesn't change!
            this.Size = new System.Drawing.Size
                            ((int)((newSize.Width + 2 * _margin) * _zoom),
                            (int)((newSize.Height + 2 * _margin) * _zoom));
            Invalidate();
        }