public void EditCustomer()
{
MessageBoxResult boxResult = MessageBox.Show
("Er du sikker på at du vil redigere kunden?", "Bekræftelse", MessageBoxButton.YesNo);
if (boxResult == MessageBoxResult.Yes)
{
CustomerMethods.EditCustomer(CustToEdit);
Application.Current.Windows.OfType <Window>().SingleOrDefault(x => x.IsActive).Close();
}
}