.NET Framework Standard Library Annotated Reference, Volume 1: Base Class Library and Extended Numerics Library

Example

using System;
namespace Samples
{
  public class EventHandlerSample
  {
    public class MyButton
    {
      public event EventHandler MouseClick;
      public void SimulateButtonClicked()
      {
        if(MouseClick != null)
          MouseClick(this, EventArgs.Empty);
      }
    }
    public static void Main()
    {
      MyButton b =  new MyButton();
      b.MouseClick += new EventHandler(ButtonClicked);
      b.SimulateButtonClicked();
    }
    public static void ButtonClicked(object sender,
                                     EventArgs args)
    {
      Console.WriteLine("Sender is {0}", sender);
    }
  }
}

The output is

Sender is Samples.EventHandlerSample+MyButton