DetectShutdown_WndProc.cs

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

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

        private static int WM_QUERYENDSESSION = 0x11;
        protected override void WndProc(ref System.Windows.Forms.Message m)
        {
            if (m.Msg == WM_QUERYENDSESSION)
            {
                File.WriteAllText(@"C:\Users\uname\Desktop\success.txt", "SUCESS");
                Environment.Exit(0);
            }
            else
            {
                label1.Text = "Nothing happends for now.";
            }

            base.WndProc(ref m);
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            
        }
    }
}