code: def handle_relative(self, event):
          
          delta_x, delta_y = self._get_relative(event)
          if delta_x:
              self.events.append(
                  self.emulate_rel(0x00,
                                   delta_x,
                                   self.timeval))
          if delta_y:
              self.events.append(
                  self.emulate_rel(0x01,
                                   delta_y,
                                   self.timeval))
docs: Relative mouse movement.