Sets the default comparison function used when sorting to be @sort_func.
If the current sort column id of @sortable is
%GTK_TREE_SORTABLE_DEFAULT_SORT_COLUMN_ID, then the model will sort using
this function.
If @sort_func is %NULL, then there will be no default comparison function.
This means that once the model has been sorted, it can’t go back to the
default state. In this case, when the current sort column id of @sortable
is %GTK_TREE_SORTABLE_DEFAULT_SORT_COLUMN_ID, the model will be unsorted.
Sets the default comparison function used when sorting to be @sort_func. If the current sort column id of @sortable is %GTK_TREE_SORTABLE_DEFAULT_SORT_COLUMN_ID, then the model will sort using this function.
If @sort_func is %NULL, then there will be no default comparison function. This means that once the model has been sorted, it can’t go back to the default state. In this case, when the current sort column id of @sortable is %GTK_TREE_SORTABLE_DEFAULT_SORT_COLUMN_ID, the model will be unsorted.