how to show a window only one time? <p>I want display a window only one time. When the user click on this button:</p> <pre><code>private void Notification_Click(object sender, RoutedEventArgs e) { NotificationSettings notifications = new NotificationSettings(); notifications.ShowDialog(); } </code></pre> <p>this will create a new window, I want that if there is already a window opened the user can't open a new one. There is an option in xaml for tell to compiler this? I remember the vb.net with windows form that allow to set the option to show only one windows at time. </p> <p>Thanks.</p>