public void Close()
            {
                var content = SurrogateContent;

                if (content != null)
                {
                    content.OnClosing();
                    content.OnDestroy();
                    SurrogateContent = null;
                }
            }
            public SurrogatedMdiChildContentProxy(SurrogatedMdiChild content)
            {
                Contract.Requires(content != null);

                this.SurrogateContent = content;
            }
        public void ShowWindow(SurrogatedMdiChild child)
        {
            Contract.Requires(child != null);

            child.Attach(ForeignWindow);
        }