on but-ton press we will see if the mouse is over us and store data

def on_press(self, event):
        'on but-ton press we will see if the mouse is over us and store data'
        if event.inaxes != self.ax:
            return
        # contains, attrd = self.rect.contains(event)
        # if not contains: return
        # print('event contains', self.rect.xy)
        # x0, y0 = self.rect.xy
        self.press = [event.xdata], [event.ydata], event.button