gistfile1.txt

 IntPtr hWnd = IntPtr.Zero;
            Process currentProcess = Process.GetCurrentProcess();
            Process[] processes = Process.GetProcessesByName(currentProcess.ProcessName);
            foreach (Process process in processes)
            {
                // Get the first instance that is not this instance, has the
                // same process name and was started from the same file name
                // and location. 

                // Also check that the process has a valid
                // window handle in this session to filter out other user's
                // processes.

                if (process.Id != currentProcess.Id
                    && process.ProcessName == currentProcess.ProcessName
                    && process.MainModule.FileName == currentProcess.MainModule.FileName
                    && process.MainWindowHandle != IntPtr.Zero)
                {
                    hWnd = process.MainWindowHandle;
                    break;
                }
            }

            if (hWnd != IntPtr.Zero)
            {
                // Restore window if minimised. Do not restore if already in
                // normal or maximised window state, since we don't want to
                // change the current state of the window.
                if (NativeMethods.IsIconic(hWnd) != 0)
                {
                    NativeMethods.ShowWindow(hWnd, NativeMethods.SW_RESTORE);
                }

                // Set foreground window.
                NativeMethods.SetForegroundWindow(hWnd);
            }