C#线程暂停和继续操作

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

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

            Label.CheckForIllegalCrossThreadCalls = false;
        }
        
        ManualResetEvent ma = new ManualResetEvent(false);

        bool stop = false;

        //启动
        private void button1_Click(object sender, EventArgs e)
        {
            Thread thread = new Thread(Runtime);

            stop = false;

            ma.Set();// 信号打开，不阻塞当前线程

            thread.Start();
        }

        /// <summary>
        /// 线程
        /// </summary>
        void Runtime()
        {
            for (int i = 1; i <= 100; i++)
            {
                if (stop)
                {
                    return;
                }
                    
                ma.WaitOne();//根据是否收到信号判断是否阻塞当前线程

                textBox1.AppendText("计时 :" + i + "
");

                Thread.Sleep(100);
            }
        }

        //暂停
        private void button2_Click(object sender, EventArgs e)
        {
            ma.Reset();//信号关闭阻塞当前线程

            textBox1.AppendText("暂停中 :
");
        }

        //继续
        private void button3_Click(object sender, EventArgs e)
        {

            ma.Set();//信号打开，不阻塞当前线程

            textBox1.AppendText("继续计时 :
");
        }

        //停止
        private void button4_Click(object sender, EventArgs e)
        {
            stop = true;

            textBox1.AppendText("停止计时 
");
        }
    }
}