When subtitle is added, all syncPoints greater or equal than a new
        subtitle are incremented.

def _subtitlesAdded(self, path, subNos):
        """When subtitle is added, all syncPoints greater or equal than a new
        subtitle are incremented."""
        def action(current, count, model, row):
            _setSubNo(current + count, model, row)

        def count(current, nos):
            ret = 0
            for no in nos:
                if current >= no:
                    ret += 1
                    # consider: current = 0, nos = [0, 1, 2, 3]
                    # in that case, current should be prepended by all nos
                    current += 1
            return ret

        self._changeSubNos(path, subNos, count, action)