关闭MessageBox

        /**//// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main() 
        ...{
            Application.Run(new Form1());
        }

        private void button1_Click(object sender, System.EventArgs e)
        ...{
            StartKiller();
            MessageBox.Show("这里是MessageBox弹出的内容","MessageBox");
            MessageBox.Show("这里是跟随运行的窗口","窗口");
        }

        private void StartKiller()
        ...{
            Timer timer = new Timer();
            timer.Interval = 10000;    //10秒启动
            timer.Tick += new EventHandler(Timer_Tick);
            timer.Start();
        }

        private void Timer_Tick(object sender, EventArgs e)
        ...{
            KillMessageBox();
            //停止计时器
            ((Timer)sender).Stop();
        }

        private void KillMessageBox()
        ...{
            //查找MessageBox的弹出窗口,注意对应标题
            IntPtr ptr = FindWindow(null,"MessageBox");
            if(ptr != IntPtr.Zero)
            ...{
                //查找到窗口则关闭
                PostMessage(ptr,WM_CLOSE,IntPtr.Zero,IntPtr.Zero);
            }
        }

        [DllImport("user32.dll", EntryPoint = "FindWindow", CharSet=CharSet.Auto)]
        private extern static IntPtr FindWindow(string lpClassName, string lpWindowName); 

        [DllImport("user32.dll", CharSet=CharSet.Auto)]
        public static extern int PostMessage(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);

        public const int WM_CLOSE = 0x10;
    }
}