MessageBox永远不会出现？

Question

This is the code i use for exiting the app,

protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
    {
        e.Cancel = true;
        MessageBoxResult m = MessageBox.Show("Are you sure, Do you want to exit this application", "Exit Warning", MessageBoxButton.OKCancel);
        if (m == MessageBoxResult.OK)
        {
            e.Cancel = false;
            //MessageBox.Show("Working ON Exiting the app!");
            if (NavigationService.CanGoBack)
                {
                  while (NavigationService.RemoveBackEntry() != null)
                   {
                     NavigationService.RemoveBackEntry();
                   }
                }

        }
    }

The problem is that message box never appears and the value of m is taken as Cancel . What could be the problem?

Answer 1

Using

MessageBoxResult m = MessageBox.Show("Are you sure, Do you want to exit this application", "Exit Warning", MessageBoxButton.OKCancel);

will not be a wise decision, because when you keep it idle (without pressing ok or cancel) for sometime your application will exit automatically.

Pls avoid this technique!!