def parent(self, index):
        """Reimplemented from QtCore.QAbstractItemModel"""
        if not index.isValid():
            return QtCore.QModelIndex()
        p = index.internalPointer()
        if p is self._conf:
            return QtCore.QModelIndex()
        pp = p.parent
        pk = p.name
        row = (pp.scalars + pp.sections).index(pk)
        return self.createIndex(row, 0, pp)