private void Buy_product_button_Click(object sender, EventArgs e)
        {

            Product selectedProduct = listBox5.SelectedItem as Product;
            using (ISession session = SessionFactory.OpenSession())
            using (ITransaction transaction = session.BeginTransaction())
            {
                selectedProduct.ActualBuyer = Convert.ToInt32(textBox2.Text);
                session.SaveOrUpdate(selectedProduct);
                transaction.Commit();
            }


        }