LE COMPOSANT TREEVIEW

private void Form1_Load(object sender, System.EventArgs e)
{
	// on ajoute le noeud principal
	root = treeView1.Nodes.Add("root");
	TreeNode second_root;
			
	root.Nodes.Add("item 1");
	root.Nodes.AddRange(new TreeNode[] {second_root = new TreeNode("item 2"),new TreeNode("item 3"), new TreeNode("item 4")});

	foreach(TreeNode tn in root.Nodes)
	{
		tn.BackColor = Color.Chartreuse;
		tn.ForeColor = Color.DarkOrchid;
		tn.NodeFont = new Font("Times New Roman",8,FontStyle.Italic);
		tn.Text += "(modifiée)";
	}

	second_root.Parent.Nodes.Add("item 5");

	treeView1.Nodes.Remove(second_root); // ou bien  :   root.Nodes.RemoveAt(1);

	root.Expand();
}

...

private string parcourir(TreeNode tn, int indent)
{
	string stmp = "";

	foreach (TreeNode t in tn.Nodes)
	{
		stmp += indent.ToString()+" - "+t.Text+"\n";
		if (t.Nodes != null)
			stmp += parcourir(t,indent+1);
	}

	return stmp;
}