g_return_val_if_fail (cf, false);
g_return_val_if_fail (cf->datasheet, false);
g_return_val_if_fail (idx < datasheet_get_column_cnt (cf->datasheet), false);
g_return_val_if_fail (cf, false);
g_return_val_if_fail (cf->datasheet, false);
g_return_val_if_fail (idx < datasheet_get_column_cnt (cf->datasheet), false);