c# winform 自动关闭messagebox 模拟回车

using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
using System.Text; 
using System.Windows.Forms; 
using System.Runtime.InteropServices; 
   
namespace WindowsApplication1 
{ 
    public partial class AutoDeleteMessageBox : Form 
    { 
        [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; 
   
        public AutoDeleteMessageBox() 
        { 
            InitializeComponent(); 
        } 
   
        private void button1_Click(object sender, EventArgs e) 
        { 
            StartKiller(); 
            MessageBox.Show("3秒钟后自动关闭MessageBox窗口", "MessageBox"); 
        } 
   
        private void StartKiller() 
        { 
            Timer timer = new Timer(); 
            timer.Interval = 3000; //3秒启动 
            timer.Tick += new EventHandler(Timer_Tick); 
            timer.Start(); 
        } 
   
        private void Timer_Tick(object sender, EventArgs e) 
        { 
            KillMessageBox(); 
            //停止Timer 
            ((Timer)sender).Stop(); 
        } 
   
        private void KillMessageBox() 
        { 
            //按照MessageBox的标题，找到MessageBox的窗口 
            IntPtr ptr = FindWindow(null, "MessageBox"); 
            if (ptr != IntPtr.Zero) 
            { 
                //找到则关闭MessageBox窗口 
                PostMessage(ptr, WM_CLOSE, IntPtr.Zero, IntPtr.Zero); 
            } 
        } 
    } 
}