def getMouse(self):
        """
        Waits for a mouse click.
        """
        # FIXME: this isn't working during an executing cell
        self.mouse_x.value = -1
        self.mouse_y.value = -1
        while self.mouse_x.value == -1 and self.mouse_y.value == -1:
            time.sleep(.1)
        return (self.mouse_x.value, self.mouse_y.value)