窗体树形结构添加

就这些：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace day08_02Treeview
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            TreeNode tn = new TreeNode("默认节点");
            treeView1.Nodes.Add(tn);

        }

        private void button1_Click(object sender, EventArgs e)
        {
            string txt = textBox1.Text;
            TreeNode tn = new TreeNode(txt);
            TreeNode tnn = treeView1.SelectedNode;
            tnn.Nodes.Add(tn);

        }

        private void 删除ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            TreeNode se = treeView1.SelectedNode;
            se.Remove();
        }

        private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
        {
            TreeNode se = treeView1.SelectedNode;
        }
    }
}