def pointerEvent(self, x, y, buttonmask=0):
        """Indicates either pointer movement or a pointer button press or release. The pointer is
           now at (x-position, y-position), and the current state of buttons 1 to 8 are represented
           by bits 0 to 7 of button-mask respectively, 0 meaning up, 1 meaning down (pressed).
        """
        self.transport.write(pack("!BBHH", 5, buttonmask, x, y))