method add_common ?before wi =
let br = new br in
match before with
| None ->
content <- (wi, br) :: (List.filter ( ((=) wi) @@ fst ) content) ;
self#obj >>> AXOJs.Node.append wi#obj ;
self#obj >>> AXOJs.Node.append br#obj ;
| Some wii ->
content <- LList.insert_after_ content (wi,br) ( ((=) wii) @@ fst ) ;
self#obj >>> AXOJs.Node.insert_before wi#obj wii#obj ;
self#obj >>> AXOJs.Node.insert_before wi#obj br#obj ;