// Do something only if we actually pick a file
   // Use the built-in identity function as a 'T -> 'U option mapper here
   // for the case 'T being a FileInfo option and 'U being FileInfo
   let click = handler.openButton.Clicked
                 |> Event.map (fun a -> (*
                           open a file dialog,
                           get a FileInfo option from the selected file name;
                           where cancel => None *))
                 |> Event.choose id

   // Selecting an item from the menu
   let select =
       handler.openMenu.AllChildren
       |> Seq.cast<MenuItem>
       |> Seq.map (fun (i:MenuItem) -> i.Activated
                                       |> Event.map (fun a -> new FileInfo((i.Child :?> Label).Text))
                                       |> Event.filter (fun (i:FileInfo) -> i.Exists))

   // The sum of all these events
   let accumulation = select
                      |> Seq.fold Event.merge click

   // do things with a file selection event
   accumulation |> Event.add UpdateRecentFileList
   accumulation |> Event.add LoadFile
   ...