BlueSky.Windows.CustomSettingsWindow.MoveUpButton_Click C# (CSharp) Метод

        private void MoveUpButton_Click(object sender, RoutedEventArgs e)
        {
            int selidx = packagelistbox.SelectedIndex;
            if (selidx > 0 && selidx <= packagelistbox.Items.Count - 1) // if not the first item
            {
                var itm = packagelistbox.SelectedItem;
                packagelistbox.Items.Remove(itm);
                packagelistbox.Items.Insert(selidx - 1, itm);
                packagelistbox.SelectedIndex = selidx - 1;
                //ApplyPackageButton.IsEnabled = true;
            }
        }