private void BtnAdd_Click(object sender, RoutedEventArgs e)
        {
            var view = new AddCustomerView();

            ViewManager.AddUserControl(view);
            ViewManager.OpenUserControl(view);

            e.Handled = true;
        }
        private void Edit_Click(object sender, RoutedEventArgs e)
        {
            var obj      = (ButtonWithObject)sender;
            var customer = (Customer)obj.Object;

            var view = new AddCustomerView(customer);

            ViewManager.AddUserControl(view);
            ViewManager.OpenUserControl(view);
        }