void gtk_map_list_model_set_map_func ( GtkMapListModel* self, GtkMapListModelMapFunc map_func, gpointer user_data, GDestroyNotify user_destroy )
Sets the function used to map items.
The function will be called whenever an item needs to be mapped and must return the item to use for the given input item.
GtkMapListModel may call this function multiple times
on the same item, because it may delete items it doesn’t need anymore.
GTK makes no effort to ensure that
map_func conforms to the item type
self. It assumes that the caller knows what they are doing and the map
function returns items of the appropriate type.