'Replace any ``\'->\'`` text strings with arrows (char \256, in
symbol font).  This searches the whole buffer, but is fast
enough to be done anytime they press \'>\'.'

def _replace_arrows(self, *e):

    arrow = '1.0'
    while True:
        arrow = self._textwidget.search('->', arrow, 'end+1char')
        if (arrow == ''):
            break
        self._textwidget.delete(arrow, (arrow + '+2char'))
        self._textwidget.insert(arrow, self.ARROW, 'arrow')
        self._textwidget.insert(arrow, ' DCTB ')
    arrow = '1.0'
    while True:
        arrow = self._textwidget.search(self.ARROW, (arrow + '+1char'), 'end+1char')
        if (arrow == ''):
            break
        self._textwidget.tag_add('arrow', arrow, (arrow + '+1char'))
