'This will be called if an event involving a button other than
2 or 3 occcurs.  This will add a label to a contour.'

def button1(self, event):

    if (event.inaxes == self.cs.ax):
        self.cs.add_label_near(event.x, event.y, self.inline, inline_spacing=self.inline_spacing, transform=False)
        self.fig.canvas.draw()
    else:
        BlockingInput.pop(self)
