    def _underline(self):
        # Underline text
        up = self.font.underline_position
        ut = self.font.underline_thickness
        w = self.font._string_width(self.text)
        s = '%.2f %.2f %.2f %.2f re f' % (self.cursor.x,
            self.cursor.y_prime - up, w, ut)
        return s
