委托 在其他类中修改form中的控件属性

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

namespace WindowsFormsApplication2
{
    
    public partial class Form1 : Form
    {

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            TestDelegate td = new TestDelegate();
            td.cb = SafeSetText;
            Thread th = new Thread(new ThreadStart(td.Test));
            th.Start();
        }

        public  void SafeSetText(string text)
        {
            if (this.InvokeRequired)
            {
                _SafeSetTextCall call = delegate(string s)
                {
                    this.label1.Text = s;
                };

                this.Invoke(call, text);
            }
            else
                this.label1.Text = text;
        }

        public delegate void _SafeSetTextCall(string text); 
    }
}