C#实现将窗体固定在显示器的左上角且不能移动的方法

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Runtime.InteropServices;
namespace App
{
 public partial class Form4 : Form
 {
  public Form4()
  {
   InitializeComponent();
   this.StartPosition = FormStartPosition.Manual;
   this.Location = new Point(0,0);
  }
  protected override void WndProc(ref Message m)
  {
   base.WndProc(ref m);
   if (m.Msg == 0x84 && m.Result == (IntPtr)2) //不让拖动标题栏 
   {
    m.Result = (IntPtr)1;
   }
   if (m.Msg == 0xA3) //双击标题栏无反应 
   {
    m.WParam = System.IntPtr.Zero;
   }
  }
 }
}