SysTray.cs

// Compile with:
// csc /target:winexe SysTray.cs

using System;
using System.Drawing;
using System.Windows.Forms;

namespace MyTrayApp {
    public class SysTrayApp : Form {
        [STAThread]
        public static void Main() {
            Application.Run(new SysTrayApp());
        }

        private NotifyIcon  trayIcon;
        private ContextMenu trayMenu;

        public SysTrayApp() {
            // Create a simple tray menu with only one item.
            trayMenu = new ContextMenu();
            trayMenu.MenuItems.Add("Exit", OnExit);

            // Create a tray icon. In this example we use a standard system icon
            trayIcon      = new NotifyIcon();
            trayIcon.Text = "MyTrayApp";
            trayIcon.Icon = new Icon(SystemIcons.Application, 40, 40);

            // Add menu to tray icon and show it.
            trayIcon.ContextMenu = trayMenu;
            trayIcon.Visible     = true;
        }

        protected override void OnLoad(EventArgs e) {
            Visible       = false; // Hide form window.
            ShowInTaskbar = false; // Remove from taskbar.
            base.OnLoad(e);
        }

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

        protected override void Dispose(bool isDisposing) {
            if (isDisposing) {
                trayIcon.Dispose(); // Release the icon resource.
            }
            base.Dispose(isDisposing);
        }
    }
}