private void DeleteFolder_Click(object sender, RoutedEventArgs e)
        {
            if (FolderListbox.SelectedItems != null)
            {
                Debug.WriteLine("SelectedItems is NOT null!");

                var selectedFiles = FolderListbox.SelectedItems.Cast <string>().ToList();

                foreach (var item in selectedFiles)
                {
                    //printCollection(MyFolders);
                    MyFolders.Remove(item);
                    //Debug.WriteLine(item);
                    PrintCollection(MyFolders);
                }
            }
            else
            {
                Debug.WriteLine("SelectedItems is null!");
            }
        }