难得今天积极的帮别人回答问题，顺便贴出来。这可能是学习事件的最简单的例子了

using System;

namespace ComboBoxEx_test
{
 /// <summary>
 /// eventtest 的摘要说明。
 /// </summary>
 public class eventTest
 {
  public eventTest()
  {
   //
   // TODO: 在此处添加构造函数逻辑
   //
  }
  public delegate void stateChange();
  public event stateChange onStateChange;
  private bool state = false;
  public bool State
  {
   get{return state;}
   set{state = value;this.onStateChange();}
  }
 }
}

调用：

private void button1_Click(object sender, System.EventArgs e)
  {
   eventTest aeventTest = new eventTest();
   aeventTest.onStateChange +=new ComboBoxEx_test.eventTest.stateChange(aeventtest_onStateChange);
   aeventTest.State = false;
  }

  private void aeventtest_onStateChange()
  {
   MessageBox.Show("Change!");
  }