'Set text up so it draws in the right place.
Currently support \'left\', \'center\' and \'right\''

def _set_text_position(self, renderer):

    bbox = self.get_window_extent(renderer)
    (l, b, w, h) = bbox.bounds
    self._text.set_verticalalignment(u'center')
    y = (b + (h / 2.0))
    if (self._loc == u'center'):
        self._text.set_horizontalalignment(u'center')
        x = (l + (w / 2.0))
    elif (self._loc == u'left'):
        self._text.set_horizontalalignment(u'left')
        x = (l + (w * self.PAD))
    else:
        self._text.set_horizontalalignment(u'right')
        x = (l + (w * (1.0 - self.PAD)))
    self._text.set_position((x, y))
