How to implement a Dismiss dialog button?

[AArnott]

Within my gui.cs application, I have a menu item command handler implemented as:

            Application.Run(new TestWindow()
            {
                Width = 80,
                Height = 15,
            });

I have my TestWindow class implemented with a constructor that starts with:

        internal TestWindow()
            : base("I/O test")
        {
            var dismissButton = new Button("Dismiss");
            dismissButton.Clicked += () => Application.RequestStop();
            this.AddButton(dismissButton);

When I click the dismiss button, the dialog disappears but sometimes it will reappear, but with no controls in it. Using Ctrl-Q to dismiss the dialog at this point is the only way to get unblocked, but it quits the app completely. Using that keystroke on the initial dialog never creates the issue in the first place. How should I be implementing my dismissButton.Clicked event handler?

[AArnott]

Oh, it appears that an async task that refreshed the UI in the dialog may have been calling this.Redraw(this.Bounds); after the dialog had been dismissed. Checking that it had not already been dismissed before this call seems to have fixed the problem.