public bool Combine(IRenderer cand)
            {
                if (_renderer == null)
                {
                    return(false);
                }

                if (cand is ScaleRenderer && cand != this &&
                    ((ScaleRenderer)cand).MinimumScale == this.MinimumScale &&
                    ((ScaleRenderer)cand).MaximumScale == this.MaximumScale)
                {
                    return(_renderer.Combine(((ScaleRenderer)cand).Renderer));
                }

                return(false);
            }