Form1.cs

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

        private void showToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.Show();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void Form1_Move(object sender, EventArgs e)
        {
            if (this.WindowState == FormWindowState.Minimized)
            {
                this.Hide();
                notifyIcon1.ShowBalloonTip(1000, "Important notice", "Something Important has come up. Click this to know more.", ToolTipIcon.Info);
            }
        }

        private void Form1_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            this.Show();
        }
    }
}