public Card AddItem1(MerchendiseWindowViewModel merch)
 {
     if (addItem == null)
     {
         addItem = new Card(merch);
     }
     return addItem;
 }
        private void createCard()
        {

            if (addItem == null)
            {
                addItem = new Card();
                addItem.Show();
            }
            
        }