MessageBox.Show causing change in cursor not to be picked up

Question

I've got a standard WPF MainWindow class, and what I'd like is to show a message box using System.Windows.MessageBox , get a response from the user and then run a long running operation (simulated below by a call to Sleep(...) ). I'd like to set the cursor to Cursors.Wait before the operation, and back to normal at the end. Here's what I've got:

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void ui_button_Click(object sender, RoutedEventArgs e)
    {
        if (MessageBox.Show("Do you want to change the background?", "Change background", MessageBoxButton.YesNo) == MessageBoxResult.No)
        {
            return;
        }

        Cursor = Cursors.Wait;

        Dispatcher.BeginInvoke(DispatcherPriority.Normal, new Action(() =>
            {
                System.Threading.Thread.Sleep(1500);

                if (Background != Brushes.Green)
                {
                    Background = Brushes.Green;
                }
                else
                {
                    Background = Brushes.White;
                }
                Cursor = Cursors.Arrow;
            }));
    }
}

This doesn't work: the cursor never appears as the wait cursor. However, if I comment out the MessageBox lines, it does work. What's going on here, and how can I get it to work as intended?

Answer 1

The following code works for me: instead of

Cursor = Cursors.Wait;

try this:

Mouse.OverrideCursor = Cursors.Wait;
Mouse.UpdateCursor();

You turn off the wait cursor the opposite way:

Mouse.OverrideCursor = null;
Mouse.UpdateCursor();

Answer 2

You run background change in the same UI thread as cursor change. Sure it`s busy with Sleep so it doesn`t show cursor change. Just make example as it should be (with several threads) and everything will be fine!

 private void ui_button_Click(object sender, RoutedEventArgs e)
  {
     if (MessageBox.Show("Do you want to change the background?", "Change background", MessageBoxButton.YesNo) == MessageBoxResult.No)
     {
        return;
     }

     Cursor = Cursors.Wait;

     BackgroundWorker bw = new BackgroundWorker();
     bw.DoWork += BwOnDoWork;
     bw.RunWorkerCompleted += BwOnRunWorkerCompleted;
     bw.RunWorkerAsync();
  }

  private void BwOnRunWorkerCompleted(object sender, RunWorkerCompletedEventArgs runWorkerCompletedEventArgs)
  {
     if (Background != Brushes.Green)
     {
        Background = Brushes.Green;
     }
     else
     {
        Background = Brushes.White;
     }
     Cursor = Cursors.Arrow;
  }

  private void BwOnDoWork(object sender, DoWorkEventArgs doWorkEventArgs)
  {
     System.Threading.Thread.Sleep(1500);
  }

Answer 3

try

DialogResult dialogResult = MessageBox.Show("Do you want to change the background?", "Change background", MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.No)
{
    return;
}

instead of

if (MessageBox.Show("Do you want to change the background?", "Change background", MessageBoxButton.YesNo) == MessageBoxResult.No)

Answer 4

Try putting your code that you want to run in other thread

     ThreadPool.QueueUserWorkItem(delegate
     {
       //your code here...
     });