pub trait TreeSortableExtManual: IsA<TreeSortable> + Sealed + 'static {
// Provided methods
fn set_default_sort_func<F>(&self, sort_func: F)
where F: Fn(&TreeModel, &TreeIter, &TreeIter) -> Ordering + 'static { ... }
fn set_sort_func<F>(&self, sort_column_id: SortColumn, sort_func: F)
where F: Fn(&TreeModel, &TreeIter, &TreeIter) -> Ordering + 'static { ... }
fn sort_column_id(&self) -> Option<(SortColumn, SortType)> { ... }
fn set_sort_column_id(&self, sort_column_id: SortColumn, order: SortType) { ... }
fn set_unsorted(&self) { ... }
}