    def __call__(self, *arg):
        if self.status:
            # If the checkbox was previously checked, set the status
            # to 0 and turn the whole box back to white.
            self.status = 0
            self.image.fill((255, 255, 255))

            # Draw the checkbox on the external surface
            ptg.Button.set_position(self, self.position, self.midpoint,
                                    self.surface)
        else:
            # If the checkbox was previously unchecked, set the status
            # to 1 and draw a check in the center of the checkbox.
            self.status = 1
            if self.checktype == 'r':
                self.draw_rect_check()
            elif self.checktype == 'c':
                self.draw_circle_check()

            # Draw the new image on the external surface
            ptg.Button.set_position(self, self.position, self.midpoint,
                                    self.surface)