'Force the update of the ticks and ticklabels. This must be
called whenever the tick locator and/or tick formatter changes.'

def update_ticks(self):

    ax = self.ax
    (ticks, ticklabels, offset_string) = self._ticker()
    if (self.orientation == u'vertical'):
        ax.yaxis.set_ticks(ticks)
        ax.set_yticklabels(ticklabels)
        ax.yaxis.get_major_formatter().set_offset_string(offset_string)
    else:
        ax.xaxis.set_ticks(ticks)
        ax.set_xticklabels(ticklabels)
        ax.xaxis.get_major_formatter().set_offset_string(offset_string)
