C# 画线以及线程

 private Pen pen1;
        private Graphics g;
        public Form1()
        {
            InitializeComponent();
            this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
            this.Load += new EventHandler(Form1_Load);
            this.Closing += new CancelEventHandler(Form1_Closing);
        }

        void Form1_Closing(object sender, CancelEventArgs e)
        {
            pen1.Dispose();
            g.Dispose();
        }

        void Form1_Load(object sender, EventArgs e)
        {
            pen1 = new Pen(Color.DarkRed, 2);
            g = this.CreateGraphics();
        }

        private void button1_Click(object sender, EventArgs e)
        {
         //   Rectangle rec = Screen.PrimaryScreen.Bounds;
         //   Rectangle res = Screen.PrimaryScreen.WorkingArea;
            pen1.DashStyle = System.Drawing.Drawing2D.DashStyle.Solid;
            g.DrawLine(pen1, 10, 10, 100, 100);
            Thread myThread = new Thread(new ThreadStart(threadRun));
            myThread.Start();
            
        }

        private void threadRun()
        {
            AddToView("Thread Run");
        }

        private void AddToView(String str)
        {
            Invoke(new EventHandler(toView), str);
        }

        private void toView(object sender, EventArgs e)
        {
            label1.Text = sender.ToString();
        }