Program.cs

using System;
using System.Windows.Forms;
using System.Threading;
using System.Runtime.InteropServices;
using System.Threading.Tasks;
using Velopack;
using Velopack.Sources;

namespace WindowsSmartTaskbar
{
    internal static class Program
    {
        static Mutex? mutex = null;
        [DllImport("user32.dll")] private static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);
        public const int HWND_BROADCAST = 0xffff;
        public static readonly int WM_SHOWME = RegisterWindowMessage("WM_SHOWME_SMARTTASKBAR");
        [DllImport("user32.dll")] public static extern int RegisterWindowMessage(string message);

        [STAThread]
        static void Main(string[] args)
        {
            VelopackApp.Build().Run();

            bool createdNew;
            mutex = new Mutex(true, "WindowsSmartTaskbar_SingleInstance_App", out createdNew);
            if (!createdNew)
            {
                SendMessage((IntPtr)HWND_BROADCAST, WM_SHOWME, 0, 0);
                return;
            }

            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            bool autostart = false;
            foreach (var arg in args)
            {
                if (arg.Trim('"', '\'').Equals("-autostart", StringComparison.OrdinalIgnoreCase)) autostart = true;
            }

            // Start an invisible background task to update the app quietly
            Task.Run(async () => {
                try {
                    var source = new GithubSource("https://github.com/nRn-World/WindowsSmartTaskbar", string.Empty, false);
                    var manager = new UpdateManager(source);
                    
                    if (manager.IsInstalled) {
                        var newVersion = await manager.CheckForUpdatesAsync();
                        if (newVersion != null) {
                            await manager.DownloadUpdatesAsync(newVersion);
                            // Updates are now ready to be applied next time the app starts/restarts naturally
                        }
                    }
                } catch { 
                    // Ignore fail silently if internet is down, rate limit, etc.
                }
            });

            Application.Run(new MainForm(autostart));
        }
    }
}