Fired either when no component was in focus during a keystroke or if the focused component and all its parent
containers chose not to handle the event. This event listener should also return true if the event
was processed in any way that requires the TextGUI to update itself, otherwise false.
textGUI - TextGUI that had the event
keyStroke - Keystroke that was unhandled
If the outcome of this KeyStroke processed by the implementer requires the TextGUI to re-draw, return
true here, otherwise false