treeview节点展开，同级节点关闭

private void treeView_dev_AfterExpand(object sender, TreeViewEventArgs e)
        {
            TreeNodeCollection tnc = null;
            if (e.Node.Parent == null)
            {
                tnc = ((TreeView)sender).Nodes;
            }
            else
                tnc = e.Node.Parent.Nodes;
            foreach (TreeNode node in tnc)
            {
                if (node != e.Node)
                {
                    node.Collapse();
                }
            }
        }

如上所示... ...