using System.Threading;

//複数スレッドから、コントロールにアクセス
private void button1_Click(object sender, System.EventArgs e)
{
	Thread thread1 = new Thread(new ThreadStart(ThreadNodeAdder));
	thread1.Start();
	Thread thread2 = new Thread(new ThreadStart(ThreadNodeAdder));
	thread2.Start();
}

//----------------------------------------------------------------------------------------------

//デリゲートの宣言
delegate void AddNodeViewDelegate();

//デリゲートのインスタンス
private AddNodeTreeViewDelegate addNodeTreeViewDelegate = new AddNodeTreeViewDelegate(AddNodeTreeView);

private void AddNodeTreeView()
{
	TreeNode node = new TreeNode("New");
	treeView1.Add(node);
}

//公開メソッド
public void ThreadNodeAdder()
{
	IAsyncResult ar = BeginInvoke(addNodeTreeViewDelegate);	

	while(ar.IsCompleted == false)
	{
		Thread.Sleep(100);
	}
}