AddonManager.MainForm.listBox_DragDrop C# (CSharp) Метод

        private void listBox_DragDrop(object sender, DragEventArgs e)
        {
            ListBox targetListBox = (ListBox)sender;
            List<string> items = targetListBox.Items.Cast<String>().ToList();

            string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
            foreach (string file in files)
            {
                if (!File.Exists(file))
                    continue;

                string fileName = Path.GetFileName(file);
                try
                {
                    int targetIndex = items.IndexOf(items
                                    .Where(itemText => itemText.StartsWith(fileName))
                                    .First());

                    items[targetIndex] = String.Format("{0} ({1})", fileName, file);
                    log.InfoFormat("Updated {0} on {1}.", fileName, targetListBox.Name);
                }
                catch (InvalidOperationException)
                {
                    items.Add(String.Format("{0} ({1})", fileName, file));
                    log.InfoFormat("Added file {0} to {1}.", file, targetListBox.Name);
                }
                catch (ArgumentNullException)
                {
                    items.Add(String.Format("{0} ({1})", fileName, file));
                    log.InfoFormat("Added file {0} to {1}.", file, targetListBox.Name);
                }
            }
            addItemsWithNaturalOrder(ref targetListBox, items);
        }
        private void checkedListBox_DragDrop(object sender, DragEventArgs e)