anchor.diff:            if item.IsCompleted then FontStyles.Italic else FontStyles.Normal
   
           // This updates the underlying item in response to a click on the
  -        // completed check box.
  +        // completed checkbox.
           Stream.ofObservableOnMain control.IsCompleted.Click
           |> Stream.subscribeJob (fun _ -> onMain {
              let isCompleted = control.IsCompleted.IsChecked.Value
  
positive.code: module Id =
    let mutable private id = 0L
  
    /// Returns a new unique id.
    let next () = Interlocked.Increment &id
  
  [<STAThread; EntryPoint>]
  
negative.code:          main.CompleteAll.IsChecked <- Nullable<bool> allCompleted })
  
        // This makes all ToDo items as either completed or active depending on
        // the state of the CompleteAll checkbox when it is clicked.
        Stream.ofObservableOnMain main.CompleteAll.Click
        |> Stream.subscribeJob (fun _ ->
           onMain { return main.CompleteAll.IsChecked.Value } >>= fun isCompleted ->
  