重写c# winform窗体关闭按钮

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;
            }
        }