How to run an application with only one instance on WinCE Platform ?

Thanks Sam for your reply.
Though , there are no 'kernel32.dll' and 'user32.dll' on WinCE ,we can still use 'coredll.dll' instead, and here is the solution i take finally,as :

static class Program
{
        #region WinCE Platform,restrict multi-instance of application,by kevin

        [DllImport("coredll.dll")]
        private static extern bool ShowWindow(System.IntPtr hWnd, int cmdShow);
        [DllImport("coredll.dll")]
        private static extern bool SetForegroundWindow(System.IntPtr hWnd);
        [DllImport("coredll.dll")]
        public static extern System.IntPtr FindWindowW(string strclass, string strname);

        public static Boolean IsApplicationRunning(string Caption)
        {
            System.IntPtr AppHandle = FindWindowW(null, Caption);
            if (AppHandle.ToInt32() > 0)
            {
                return true;
            }
            return false;
        }

        public static void BringAppToTop(string Caption)
        {
            System.IntPtr AppHandle = FindWindowW(null, Caption);
            if (AppHandle.ToInt32() > 0)
            {
                SetForegroundWindow(AppHandle);
            }
        }

        #endregion
        ///

        /// application entry point
        ///

        [MTAThread]
        static void Main()
        {
            if (Program.IsApplicationRunning("LogIn") == true)
            { 
                MessageBox.Show("Application is running...");
                Program.BringAppToTop("LogIn");
                return;
            }
            else
            {
                Application.Run(new FLoginPDA());
            }
        }
}