Запуск программы в фоновом режиме

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;
using Microsoft.VisualBasic.ApplicationServices;
 
static class Program
{
    /// <summary>
    /// Главная точка входа для приложения.
    /// </summary>
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
 
        try
        {
            SingleInstanceApplication.Run(new MainForm(), StartupNextInstanceHandler);
            //Application.Run(new MainForm());
        }
        catch (Exception e)
        {
            MessageBox.Show(e.Message, "Error!", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
    }
 
    static void StartupNextInstanceHandler(
    object sender, StartupNextInstanceEventArgs e)
    {
    }
}
 
public class SingleInstanceApplication : WindowsFormsApplicationBase
{
    private SingleInstanceApplication()
    {
        base.IsSingleInstance = true;
    }
 
    public static void Run(Form f,
        StartupNextInstanceEventHandler startupHandler)
    {
        SingleInstanceApplication app = new SingleInstanceApplication();
        app.MainForm = f;
        app.StartupNextInstance += startupHandler;
        app.Run(Environment.GetCommandLineArgs());
    }
}

public static void Run(StartupNextInstanceEventHandler startupHandler) {
    SingleInstanceApplication app = new SingleInstanceApplication();
    app.StartupNextInstance += startupHandler;
    app.Run(Environment.GetCommandLineArgs());
}

SingleInstanceApplication.Run(StartupNextInstanceHandler);

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.Runtime.InteropServices;
 
namespace WindowsFormsApplication1 {
   
    public partial class Form1 : Form {
        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        static extern bool ShowWindow(IntPtr hWnd, int showCmds);
 
        public Form1() {
            InitializeComponent();
            IntPtr wnd = this.Handle;
            ShowWindow(wnd, 6);
        }
    }
}