代码如下：

using System;
using System.Collections.Generic;
using using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace regist
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

        }

        private void btnClose_Click(object sender, EventArgs e)
        {
            Application.ExitThread();
        }

        private void txtName_Validating(object sender, CancelEventArgs e)
        {


            if (txtName.Text.Trim() == string.Empty)
            {
                MessageBox.Show("用户名为空，请重新输入！");
                txtName.Focus();
            }
        }

        private void txtPwd1_Validating(object sender, CancelEventArgs e)
        {
            if (txtPwd1.Text.Trim() == string.Empty)
            {
                MessageBox.Show("密码为空，请重新输入！");
                txtPwd1.Focus();
            }
        }

        private void txtPwd2_Validating(object sender, CancelEventArgs e)
        {
            if (txtPwd2.Text.Trim() == string.Empty || txtPwd2.Text != txtPwd1.Text)
            {
                MessageBox.Show("两次密码不一致　　请重新输入！");
                txtPwd2.Focus();
            }
        }

        private void txtEmail_Validating(object sender, CancelEventArgs e)
        {
            if (txtEmail.Text.Trim() == string.Empty || txtEmail.Text.Contains("@") == false)
            {
                MessageBox.Show("邮件地址格式错误，请重新输入！");
                txtEmail.Focus();
            }
        }

        private void txtName_Enter(object sender, EventArgs e)
        {
            txtMsg.Text = "请输入您的名字";
        }

        private void txtPwd1_Enter(object sender, EventArgs e)
        {
            txtMsg.Text = "请输入您的密码";
        }

        private void txtPwd2_Enter(object sender, EventArgs e)
        {
            txtMsg.Text = "请再次输入您的密码";
        }

        private void txtEmail_Enter(object sender, EventArgs e)
        {
            txtMsg.Text = "请输入您的邮箱地址";
        }

        private void btnOk_Click(object sender, EventArgs e)
        {

        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {

            DialogResult result;
            result = MessageBox.Show("确定退出吗？", "退出", MessageBoxButtons.OKCancel, MessageBoxIcon.Question);
            if (result == DialogResult.OK)
            {

                Application.ExitThread();
            }
            else
            {
                e.Cancel = true;
            }

        }
    }
}

当我点击右上角的×时    总是弹出那个mbx    不知道怎么解决    自己的思路是    是否在点击×的事件里  添加一段代码   功能就是把控件屏蔽掉
牛人看看啊   还有就是我的退出按钮没有用