title: ZK @listen annotation
body: <p>I have the following problem: I have a zk page which contains four groupbox, whose id are "id_gb1", "id_gb2", "id_gb3" and "id_gb4".
  I created a Java controller (extending GenericForwardComposer) in which I have the following lines:</p>
  
  <pre><code>[...]
  @Listen("onClick = #id_gb1; onClick = #id_gb2; onClick = #id_gb3; onClick = #id_gb4")
  private void onClick() {
    //do some stuff
  }
  [...]
  </code></pre>
  
  <p>and I set the value of the attribute apply of the window element in the zk file with the class name.
  The problem is that when I click on the label of the groupbox nothing appens: furthermore, if I write in the same Java controller</p>
  
  <pre><code>[...]
  public void onClick$id_gb1() {
    //do some stuff
  }
  [...]
  </code></pre>
  
  <p>it works!</p>
  
  <p>Does anyone know what I'm doing wrong?
  Thanks,
  Daniele</p>