'Set the location of tick in data coords with scalar *loc*'

def update_position(self, loc):

    if self.tick1On:
        self.tick1line.set_ydata((loc,))
    if self.tick2On:
        self.tick2line.set_ydata((loc,))
    if self.gridOn:
        self.gridline.set_ydata((loc,))
    if self.label1On:
        self.label1.set_y(loc)
    if self.label2On:
        self.label2.set_y(loc)
    self._loc = loc
    self.stale = True
