C#線程暫停和繼續操作

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;

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

            stop = false;

            ma.Set();// 信號打開，不阻塞當前線程

            thread.Start();
        }

        /// <summary>
        /// 線程
        /// </summary>
        void Runtime()
        {
            for (int i = 1; i <= 100; i++)
            {
                if (stop)
                {
                    return;
                }
                    
                ma.WaitOne();//根據是否收到信號判斷是否阻塞當前線程

                textBox1.AppendText("計時 :" + i + "\r\n");

                Thread.Sleep(100);
            }
        }

        //暫停
        private void button2_Click(object sender, EventArgs e)
        {
            ma.Reset();//信號關閉阻塞當前線程

            textBox1.AppendText("暫停中 :\r\n");
        }

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

            ma.Set();//信號打開，不阻塞當前線程

            textBox1.AppendText("繼續計時 :\r\n");
        }

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

            textBox1.AppendText("停止計時 \r\n");
        }
    }
}