private void ListBox_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
 {
     if (Facts.SelectedItem != null)
     {
         var viewModel = (ChuckNorrisFactViewModel)Facts.SelectedItem;
         DetailsView.SetViewModel(viewModel);
     }
 }
 private void ButtonClean_OnClick(object sender, RoutedEventArgs e)
 {
     Facts.Items.Clear();
     DetailsView.SetViewModel(null);
 }