How do you display a custom UserControl as a dialog?

Question

How do you display a custom UserControl as a dialog in C#/WPF (.NET 3.5)?

Answer 1

If the answer by 'sixlettervariables' is modified as so, it works

private void button1_Click ( object sender, RoutedEventArgs e )                  
{
    Window window = new Window
    {
        Title = "My User Control Dialog",
        Content = new UserControl ( ),
        Height = 200,  // just added to have a smaller control (Window)
        Width = 240
    };

    window.ShowDialog ( );
}