Fills in @sort_column_id and @order with the current sort column and the order. It returns %TRUE unless the @sort_column_id is %GTK_TREE_SORTABLE_DEFAULT_SORT_COLUMN_ID or %GTK_TREE_SORTABLE_UNSORTED_SORT_COLUMN_ID.
The sort column id to be filled in
The #GtkSortType to be filled in
%TRUE if the sort column is not one of the special sort column ids.
See Implementation
Fills in @sort_column_id and @order with the current sort column and the order. It returns %TRUE unless the @sort_column_id is %GTK_TREE_SORTABLE_DEFAULT_SORT_COLUMN_ID or %GTK_TREE_SORTABLE_UNSORTED_SORT_COLUMN_ID.