當點擊'待處理工作'時  我的待處理工作-1,我的待處理工作-2,...隱藏起來.
-------------------------------------------------------------------------我是Trap了左键单击,看看合不合要求:
        private void treeView2_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
        {
            if (e.Button == MouseButtons.Left && e.Clicks == 1)
            {
                if (e.Node.IsExpanded)
                {
                    e.Node.Collapse();
                }
                else
                {
                    e.Node.Expand ();
                }
            }
        }