'Remove a callback that was registered with ``bind_click``.
:type button: int
:param button: Which button the user should use to click on
this ``CanvasWidget``.  Typically, this should be 1 (left
button), 3 (right button), or 2 (middle button).'

def unbind_click(self, button=1):

    try:
        del self.__callbacks[button]
    except:
        pass
