public form_loadatorigin() { InitializeComponent(); this.Loaded += new RoutedEventHandler(form_loadatorigin_Loaded); } private void form_loadatorigin_Loaded(object sender, RoutedEventArgs e) { if (!IsFirstLoaded) { IsFirstLoaded = true; formLoadUnload.SelectionChanged += new SelectionChangedEventHandler(formLoadUnload_SelectionChanged); DependencyObject d1 = VisualTreeHelper.GetChild(formLoadUnload, 0); m_NextPageButton = LogicalTreeHelper.FindLogicalNode(d1, "NextPageButton") as Button; m_NextPageButton.PreviewMouseLeftButtonDown += new MouseButtonEventHandler(m_NextPageButton_PreviewMouseLeftButtonDown); } } void m_NextPageButton_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e) { e.Handled = true; if (ValidateAndShowErrors()) { m_NextPageButton.RaiseEvent(new RoutedEventArgs(Button.ClickEvent, m_NextPageButton)); } } private Button m_NextPageButton; private bool IsFirstLoaded = false;