Creates a new GtkSorter that works by calling @sort_func to compare items.
If @sort_func is %NULL, all items are considered equal.
the GCompareDataFunc to use for sorting
user data to pass to @sort_func
destroy notify for @user_data
a new GtkCustomSorter
ConstructionException GTK+ fails to create the object.
See Implementation
Creates a new GtkSorter that works by calling @sort_func to compare items.
If @sort_func is %NULL, all items are considered equal.