method cycle_tab forward =
match active_view with
None -> ()
| Some v ->
match contents with
None -> ()
| Some mycontents ->
let rec iter c =
match find_container c mycontents with
None -> None
| Some (`Notebook gn) ->
Some gn
| Some x -> iter x
in
match iter (`View v) with
None -> ()
| Some gn -> gn#cycle_tab forward