title: GWT FocusPanel, tab key and focus handlers
body: <p>I'm implementing a custom widget extending <code>Composite</code> and implementing <code>Focusable</code> and <code>HasFocusHandlers</code>.</p>
  
  <p>The widget contains two widgets in a panel that I wrap into a <code>FocusPanel</code> that I use to initialize the widget. My constructor looks something like that:</p>
  
  <pre><code>public CustomBox() {
      panel = new VerticalPanel();
      ...
      panel.add(caption);
      panel.add(icon);
      ...
      focusPanel = new FocusPanel(panel);
      initWidget(focusPanel);
  }
  </code></pre>
  
  <p>I delegate the implementation of the <code>Focusable</code> and <code>HasFocusHandlers</code> in the focus panel, e.g:</p>
  
  <pre><code>@Override
  public void setFocus(boolean focused) {
      focusPanel.setFocus(focused);
  }
  
  @Override
  public void setTabIndex(int index) {
      focusPanel.setTabIndex(index);        
  }
  
  @Override
  public HandlerRegistration addFocusHandler(FocusHandler handler) {
      return focusPanel.addFocusHandler(handler);
  }   
  </code></pre>
  
  <p>And after that I can use <code>setFocus(true)</code> to set the focus in any of my objects, and <code>setTabIndex()</code> to set the tab index. Tab key also works as expected, but my problem is that I cannot handle focus events as the <code>onFocus()</code> method of the handlers added with <code>addFocusHandler()</code> are never called.</p>
  
  <p>I know that the focus is changing because I follow the focus of the objets changing its style with <code>:focus</code> CSS selector.</p>
  
  <p>Why are focus handlers never called?</p>