using System;

using System.Collections.Generic;

using System.Linq;

using System.Runtime.InteropServices;

using System.Threading;

using System.Threading.Tasks;

using System.Windows.Forms;

​

//http://stackoverflow.com/questions/697058/single-instance-windows-forms-application-and-how-to-get-reference-on-it

//http://stackoverflow.com/questions/2636721/bring-another-processes-window-to-foreground-when-it-has-showintaskbar-false

namespace BringToFrontLab

{

    public static class Program

    {

        /// <summary>

        /// 應用程式的主要進入點。

        /// </summary>

        [STAThread]

       public static void Main()

        {

            using (Mutex mutex = new Mutex(false, "Form1"))

            {

                if (!mutex.WaitOne(0, true))

                {

                    bringToFront("Form1");

                }

                else

                {

                    Application.EnableVisualStyles();

                    Application.SetCompatibleTextRenderingDefault(false);

                    Application.Run(new Form1());

                }

            }

        }

​

        [DllImport("USER32.DLL", CharSet = CharSet.Unicode)]

        public static extern IntPtr FindWindow(String lpClassName, String lpWindowName);

​

        [DllImport("USER32.DLL")]

        public static extern bool SetForegroundWindow(IntPtr hWnd);

​

         [DllImport("USER32.DLL")]

        public static extern bool ShowWindow(IntPtr hWnd,int i);

​

        public static void bringToFront(string title)

        {

            // Get a handle to the Calculator application.

            IntPtr handle = FindWindow(null, title);

​

            // Verify that Calculator is a running process.

            if (handle == IntPtr.Zero)

            {

                return;

            }

            ShowWindow(handle, 1);

            // Make Calculator the foreground application

            SetForegroundWindow(handle);

        }

    }

​

    public class Form1 : Form { }

}