我有一个计时器，我想将计时器回调放入单独的函数中，但是，出现此错误。

需要对象引用才能访问非静态字段，方法或属性’‘…

如果我将这些回调声明为委托事件，并将成员变量声明为静态，则可以正常工作。我应该这样吗？

class MainClass
{
    private Timer _timer = null;
    private TimeSpan _millisecs;

    public static void Main (string[] args)
    {
        Application.Init();
        MainWindow win = new MainWindow();

        Label lbl = new Label();
        lbl.Text = "00:00";

        Table tbl = new Table(2, 2, true);
        tbl.Name = "tbl";

        Button btn = new Button("Start");
        tbl.Attach(lbl, 0, 2, 0, 1);
        tbl.Attach(btn, 0, 1, 1, 2);
        Button btn_stop = new Button("Stop");
        tbl.Attach(btn_stop, 1, 2, 1, 2);

        btn.Clicked += StartClick;
        btn_stop.Clicked += StopClick;

        win.Add(tbl);
        win.ShowAll();

        Application.Run ();
    }

    private void StartClick(object obj, EventArgs args)
    {
        if (_timer == null) {
            _timer = new Timer();
            _timer.Elapsed += delegate(object sender, ElapsedEventArgs e) {
                _millisecs = _millisecs.Add(new TimeSpan(0, 0, 0, 0, 50));
                lbl.Text = new DateTime(_millisecs.Ticks).ToString("ss:ff");
            };
            _timer.Interval = 50;
            _timer.Enabled = true;                  
        }

        _timer.Start();             
    }

    private void StopClick(object obj, EventArgs args)
    {
        _timer.Stop();          
    }

}