private void ClearDemand(object sender, RoutedEventArgs e)
 {
     pvm                     = new PanPizzaViewModel();
     DataContext             = pvm;
     SizeCMB.IsEnabled       = true;
     IngredientCMB.IsEnabled = true;
     BuyBtn.IsEnabled        = false;
 }
        private void PurchaseBtn(object sender, RoutedEventArgs e)
        {
            MessageBoxResult messageBoxResult = System.Windows.MessageBox.Show("Thank you for buying our pizza!", "Notification");

            pvm                     = new PanPizzaViewModel();
            DataContext             = pvm;
            SizeCMB.IsEnabled       = true;
            IngredientCMB.IsEnabled = true;
            BuyBtn.IsEnabled        = false;
        }