title: TextBox doesn't fire Invalidated event
body: <p>Why TextBox doesn't raise Invalidated event when it's caret appear and disappear and when its text be changed ?</p>
  
  <pre><code>class Form1
  {
      TextBox t = new TextBox();
  
      public Form1()
      {
          t.Invalidated += delegate(object sender,InvalidatedEventArgs e)
          {
              //this event doesn't be fired,why ?
          };
      }
  }
  </code></pre>