public void Popup_selector()
        {
            WpfTestHelper.WithWindow(w => {
                var selector     = new PopupSelector();
                selector.Name    = "Items";
                selector.Member  = "Item.Item2";
                w.Content        = selector;
                selector.Loaded += (sender, args) => {
                    var text = selector.AsText();
                    Assert.That(text, Does.Contain("test2"));

                    WpfTestHelper.Shutdown(w);
                };
                w.DataContext = new Model();
                ViewModelBinder.Bind(w.DataContext, w, null);
            });
        }