code: def register_on_show_window(self, callback):
          
          event_type = library.VBoxEventType.on_show_window
          return self.event_source.register_callback(callback, event_type)
docs: Set the callback function to consume on show window events.
          This occurs when the console window is to be activated and brought to
          the foreground of the desktop of the host PC.
  
          Callback receives a IShowWindowEvent object.
  
          Returns the callback_id