C#

public partial class customForm : Form
{
    public event EventHandler<EventArgs> RefreshActivityEvent;
    public void LoginInvalidated(object sender, EventArgs e)
    {
    }
    protected virtual void OnRefreshActivity(object source, EventArgs e)
    {
        EventHandler<EventArgs> handler = RefreshActivityEvent;
        if (handler != null)
        {
            handler(this, e);
        }
    }
}
public class Login
{
    private System.Timers.Timer InvalidationTimer;
    public event EventHandler<EventArgs> TimedEvent;
    public string foo;

    public Login()
    {
        InvalidationTimer = new System.Timers.Timer();
        InvalidationTimer.Interval = 10000;
        InvalidationTimer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
        InvalidationTimer.AutoReset = false;
        InvalidationTimer.Start();
    }

    protected virtual void OnTimedEvent(object source, ElapsedEventArgs e)
    {
        EventHandler<EventArgs> handler = TimedEvent;
        if (handler != null)
        {
            handler(this, e);
        }
    }
    public virtual void Restart()
    {
        InvalidationTimer.Stop();
        InvalidationTimer.Start();
    }
}

FirstForm.RefreshActivityEvent += new System.EventHandler<EventArgs>(RefreshActivity);
SecondForm.RefreshActivityEvent += new System.EventHandler<EventArgs>(RefreshActivity);
LoginObject.TimedEvent += new System.EventHandler<EventArgs>(FirstForm.LoginInvalidated);
LoginObject.TimedEvent += new System.EventHandler<EventArgs>(SecondForm.LoginInvalidated);