public void OnPreviewKeyDownTest()
        {
            UITester.Dispatcher.Invoke(() =>
            {
                bool stopped = false;
                testTutorialDialog.Manager.Stopped += (_, __) => stopped = true;
                testTutorialDialog.RaiseEvent(
                    new KeyEventArgs(Keyboard.PrimaryDevice, Keyboard.PrimaryDevice.ActiveSource, 0, Key.Escape)
                {
                    RoutedEvent = Keyboard.PreviewKeyDownEvent
                });
                Assert.IsTrue(stopped);

                // for code coverage
                testTutorialDialog.RaiseEvent(
                    new KeyEventArgs(Keyboard.PrimaryDevice, Keyboard.PrimaryDevice.ActiveSource, 0, Key.Left)
                {
                    RoutedEvent = Keyboard.PreviewKeyDownEvent
                });
                testTutorialDialog.RaiseEvent(
                    new KeyEventArgs(Keyboard.PrimaryDevice, Keyboard.PrimaryDevice.ActiveSource, 0, Key.Right)
                {
                    RoutedEvent = Keyboard.PreviewKeyDownEvent
                });
                testTutorialDialog.RaiseEvent(
                    new KeyEventArgs(Keyboard.PrimaryDevice, Keyboard.PrimaryDevice.ActiveSource, 0, Key.Enter)
                {
                    RoutedEvent = Keyboard.PreviewKeyDownEvent
                });
            });
        }