title: When the DeleteEvent is called by a Gtk# window, how can I prevent the window from closing?
body: <p>When the window closes, the user is asked to save the file that they edited. They should also have an option to cancel quitting the application.  </p>
  
  <p>In WPF I can set the CancelEventArgs.Cancel property to true to do this. Is there an equivalent/workaround in Gtk#?</p>