private void buttonUserEdit_Click(object sender, EventArgs e) { if (listBoxUser.SelectedItem is Customer) { Customer c = (Customer)listBoxUser.SelectedItem; if (c.EmailAddress != FormController.CurrentCustomer.EmailAddress) { new EditDataView(c).ShowDialog(); } else { Feedback.ErrorCustomersEditHimself(); } } else { Feedback.ErrorNoSelectedItem(); } }