C#

using System;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        System.Timers.Timer timer;
        public Form1()
        {
            InitializeComponent();
            timer = new System.Timers.Timer();
            timer.Elapsed += new System.Timers.ElapsedEventHandler(timer_Elapsed);
            timer.Start();
        }

        void timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
        {
            /* System.InvalidOperationException "Cross-thread operation not valid..."
            will be thrown if you try to alter the property directly from a different thread */
            if (this.InvokeRequired)
            {
                BeginInvoke(new MethodInvoker(delegate() { UpdateText(sender, e); }));
            }
            else
            {
                UpdateText(sender, e);
            }
        }
        private void UpdateText(object sender, System.Timers.ElapsedEventArgs e)
        {
            Text = e.SignalTime.ToString();
        }
    }
}