Returns the number of columns by which the sorter sorts.
If the sorter of the primary sort column does not determine a total order, then the secondary sorters are consulted to break the ties.
Use the [signal@Gtk.Sorter:GtkColumnViewSorter:changed
] signal to get notified when the number of sort columns changes.
this |
a `GtkColumnViewSorter` |
the number of sort columns |