'Show tooltip with full path only for the root directory'

def data(self, index, role):

    if (role == Qt.ToolTipRole):
        root_dir = self.path_list[0].split(osp.sep)[(-1)]
        if (index.data() == root_dir):
            return osp.join(self.root_path, root_dir)
    return QSortFilterProxyModel.data(self, index, role)
