TreeViewNode... come lo linko alla struttura di una cartella?

using System;
using System.IO;
using System.Windows.Forms;
using System.ComponentModel;
using System.Collections.Generic;

namespace ImpronteCS
{
  class FileSystemTreeView : TreeView
  {
    /// <summary>Lista dei files caricati</summary>
    public List<string> FileList;

    /// <summary>Aggiungere le sottodirectory?</summary>
    public bool SubFolders = false;
    /// <summary>Il formato dei files da caricare</summary>
    public string Format = string.Empty;
    /// <summary>Conteggio dei file [si può omettere]</summary>
    public int FileCount = 0;

    /// <summary>Costruttore</summary>
    public FileSystemTreeView()
    {
      this.BeforeExpand += new TreeViewCancelEventHandler(FS_BeforeExpand);
      this.AfterCollapse += new TreeViewEventHandler(FS_AfterCollapse);
    }

    private void FS_AfterCollapse(object sender, TreeViewEventArgs e)
    {
      //Pulisci i nodi.
      e.Node.Nodes.Clear();
      e.Node.Nodes.Add(".");
    }

    private void FS_BeforeExpand(object sender, TreeViewCancelEventArgs e)
    {
      try
      {
        e.Node.Nodes.Clear();
        string needle = e.Node.Tag as string;
        string[] folders = Directory.GetDirectories(needle);
        string[] files = Directory.GetFiles(needle);

        //Carico le sottodirectory?
        if (SubFolders)
        {
          foreach (string folder in folders)
          {
            try
            {
              string[] s_folders = Directory.GetDirectories(folder);
              string[] s_files = Directory.GetFiles(folder);

              TreeNode t_folder = getNode(folder);

              foreach (string s_folder in s_folders)
                t_folder.Nodes.Add(getNode(s_folder));

              foreach (string s_file in s_files)
              {
                //E' il formato che voglio?
                if (s_file.EndsWith(Format))
                {
                  //Allora aggiungilo.
                  FileList.Add(s_file);
                  t_folder.Nodes.Add(getNode(s_file));
                }
              }

              e.Node.Nodes.Add(t_folder);
            }
            catch (IOException ioe)
            {
              //Fai niente
            }
            catch (UnauthorizedAccessException uae)
            {
              //Fai niente
            }
            finally
            {
              //Fai niente
            }
          }
        }

        foreach (string file in files)
        {
          //E' il formato che voglio?
          if (file.EndsWith(Format))
          {
            //Allora aggiungilo.
            FileList.Add(file);
            e.Node.Nodes.Add(getNode(file));
          }
        }
      }
      catch (IOException ioe)
      {
        //Fai niente
      }
      catch (UnauthorizedAccessException uae)
      {
        //Fai niente
      }
      finally
      {
        //Fai niente
      }
    }

    /// <summary>Carica la struttura</summary>
    /// <param name="needle">Path da cui partire</param>
    public void Load(string needle)
    {
      if (FileList == null)
        FileList = new List<string>();
      //Cancella la lista dei files.
      FileList.Clear();
      //Cancella i nodi
      this.Nodes.Clear();
      //prendi il nodo principale.
      TreeNode n_node = getNode(needle);

      n_node.Nodes.Add(".");
      this.Nodes.Add(n_node);
      //Espando il nodo root.
      this.Nodes[0].Expand();

      //Conteggia i files [si può omettere]
      FileCount = 0;
      FileSystemCounter.Count(needle, Format, SubFolders, ref FileCount);
    }

    /// <summary>Crea il nodo dell'albero</summary>
    /// <param name="path">La cartella del Nodo.</param>
    /// <returns>TreeNode</returns>
    private TreeNode getNode(string path)
    {
      TreeNode r_node = new TreeNode();
      int limit = path.LastIndexOf('\\') + 1;
      string name = path.Substring(limit, (path.Length - limit));

      if (name.Length < 1)
        name = path.Substring(0, path.Length - 1);

      r_node.Text = name;
      r_node.Tag = path;

      return r_node;
    }
  }
}