C#

class Program
{
  static void Main(string[] args)
  {
    ProductCounterWatcher w = new ProductCounterWatcher();
    ICounterProcessor p = new PrdStandStillDetector();
    w.OnCounterChanged += p.CounterChanged;
    w.Detect();
    w.OnCounterChanged -= p.CounterChanged;
  }
}
//-----------------------------------------------------------------------------------
public class ProductCounter
{
  public int Value { get; set; }
  public DateTime Timestamp { get; set; }

  public override string ToString()
  {
    return string.Format("[ProductCounter:{0},{1}]", Timestamp, Value);
  }
}
//-----------------------------------------------------------------------------------
public interface ICounterProcessor
{
  void CounterChanged(object source, CounterChangedEventArgs e); // <<<----
}
//-----------------------------------------------------------------------------------

public delegate void CounterChangedHandler(object source, CounterChangedEventArgs e); // <<<----
//-----------------------------------------------------------------------------------

public class CounterChangedEventArgs : EventArgs
{
  public ProductCounter Counter { get; set; }

  public CounterChangedEventArgs(ProductCounter counter)
  {
    this.Counter = counter;
  }
}
//-----------------------------------------------------------------------------------
public class PrdStandStillDetector : ICounterProcessor
{
  public void CounterChanged(object source, CounterChangedEventArgs e)
  {
  }
}
//-----------------------------------------------------------------------------------
public class ProductCounterWatcher
{
  public CounterChangedHandler OnCounterChanged;

  public void Detect()
  {
    if (OnCounterChanged != null) OnCounterChanged(this, new CounterChangedEventArgs(new ProductCounter() { Timestamp = DateTime.Now, Value = 1 }));
  }
}

private void DXWindow_Closing(object sender, CancelEventArgs e)
		{
			var result =
				MessageBox.Show(
							    Properties.Resources.MainWindowMsgBox3 + Environment.NewLine +
							    Properties.Resources.MainWindowMsgBox4 + Environment.NewLine + Environment.NewLine +
							    Properties.Resources.MainWindowMsgBox5,
							    Properties.Resources.MainWindowMsgBox6, MessageBoxButton.YesNo, MessageBoxImage.Question,
							    MessageBoxResult.No);
			Log.Info("User engaged Application Closure Event");
			switch (result)
			{
				case MessageBoxResult.Yes:
					Log.Info("Main Window Closed");
					OnClosed(e);
					Application.Current.Shutdown();
					break;
				case MessageBoxResult.No:
					e.Cancel = true;
					break;
			}
		}