code: def register_on_guest_mouse(self, callback):
          
          event_type = library.VBoxEventType.on_guest_mouse
          return self.event_source.register_callback(callback, event_type)
docs: Set the callback function to consume on guest mouse events.
  
          Callback receives a IGuestMouseEvent object.
  
          Example:
              def callback(event):
                  print(("%s %s %s" % (event.x, event.y, event.z))