c# 窗体菜单排列MDI

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

namespace Test02
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void 水平平铺ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            LayoutMdi(MdiLayout.TileHorizontal);
        }

        private void 垂直平铺ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            LayoutMdi(MdiLayout.TileVertical);
        }

        private void 层叠排列ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            LayoutMdi(MdiLayout.Cascade);
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void 加载子窗体ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Form2 frm2 = new Form2();
            frm2.MdiParent = this;
            frm2.Show();
            Form3 frm3 = new Form3();
            frm3.MdiParent = this;
            frm3.Show();
            Form4 frm4 = new Form4();
            frm4.MdiParent = this;
            frm4.Show();
        }
    }
}