let setter ~cont ?hadjustment ?vadjustment ?(button_actions=[])
?titles_show =
cont (fun w ->
let may_set f param = may param ~f:(f w) in
may_set set_hadjustment hadjustment;
may_set set_vadjustment vadjustment;
List.iter button_actions ~f:(fun (n,act) -> set_button_actions w n act);
may_set set_titles_show titles_show)