Simulate keyboard input in WPF

Hi,

I'm trying to simulate keyboard input using RaiseEvent and
TextComposition. My code snippet looks like:

TextComposition textComposition = new
TextComposition(InputManager.Current, txtBox, "text to input");
TextCompositionEventArgs e = new
TextCompositionEventArgs(Keyboard.PrimaryDevice, textComposition);
e.RoutedEvent = UIElement.TextInputEvent;
txtBox.RaiseEvent(e);

My question is: How to simulate an input of the tab key? Is there some
way to express that to pass to the TextComposition instance? I read
through the MSDN doc but there is no explanation as to how to achieve
this.

Thanks a lot,

Derek