'Returns the tabstop \'number\'.
\'requester\' is the class that is interested in this.'

def _get_tabstop(self, requester, number):

    if (number in self._tabstops):
        return self._tabstops[number]
    for child in self._editable_children:
        if (child is requester):
            continue
        rv = child._get_tabstop(self, number)
        if (rv is not None):
            return rv
    if (self._parent and (requester is not self._parent)):
        return self._parent._get_tabstop(self, number)
