method find_view_container gv =
let find_in_child = function
None -> None
| Some (`Notebook gn) ->
gn#find_view_container gv
| Some (`Paned gp) ->
gp#find_view_container gv
| Some (`View v) ->
if Oo.id v = Oo.id gv then
Some (`Paned (self :> gui_paned))
else
None
in
match find_in_child child1 with
None -> find_in_child child2
| Some x -> Some x