namespace Chapter1_WpfApplication1

 {

     /// <summary>

     /// Interaction logic for App.xaml

     /// </summary>

     public partial class App : Application

     {

         protected override void OnStartup(StartupEventArgs e)

         {

             base.OnStartup(e);

             this.DispatcherUnhandledException += App_DispatcherUnhandledException;

         }

         void App_DispatcherUnhandledException(object sender, System.Windows.Threading.DispatcherUnhandledExceptionEventArgs e)

         {

             throw new NotImplementedException();

         }

     }

 }