method private _cb__down_opt_button_clicked = fun () ->
match sopts_view.sopt_view#selection#get_selected_rows with
| [path] ->
if GTree.Path.get_depth path > 1 then
let path_next = GTree.Path.copy path in
GTree.Path.next path_next;
if path_is_valid sopts_store path_next then
i_bool (sopts_store#swap
(sopts_store#get_iter path)
(sopts_store#get_iter path_next))
| _ ->
()