title: selectOneButton change listener always returning null
body: <p>I'm using JSF 2 along with primefaces, i have a selectOneButton which have 2 values, EN/FR, i want to be notified each time the language is changed, and then change the locale of the page, i have set valueChangeListener and an ajax event, 
  but everytime the change listener is fired, the new value is always null!
  here is the xhtml code:</p>
  
  <pre><code>&lt;h:form id="f"&gt;
  &lt;p:selectOneButton id="lang" value="#{currentUser.language}" valueChangeListener="#{currentUser.languageChanged}" &gt;
      &lt;f:selectItem itemLabel="English" itemValue="en" /&gt;
      &lt;f:selectItem itemLabel="Françcais" itemValue="fr" /&gt;
      &lt;f:ajax event="change"/&gt;
  &lt;/p:selectOneButton&gt;
  &lt;/h:form&gt;
  </code></pre>
  
  <p>the languageChanged method for testing: </p>
  
  <pre><code>public void languageChanged(ValueChangeEvent event) {
          System.out.println("new val: " + event.getNewValue());
          System.out.println("old val: " + event.getOldValue());
      }
  </code></pre>
  
  <p>i even tried to attach to the ajax a listener:</p>
  
  <pre><code>&lt;f:ajax event="change" listener="#{currentUser.languageChanged}"/&gt;
  </code></pre>
  
  <p>and the method: </p>
  
  <pre><code>public void languageChanged(AjaxBehaviorEvent event) {
          SelectOneButton button = (SelectOneButton)event.getComponent(); 
          System.out.println(button.getValue())   ;
      }
  </code></pre>
  
  <p>Is this the wrong way to retrieve the new selected value from a p:selectOneButton   with ajax?</p>
  
  <p>UPDATE:
  So i know what is causing this problem
  actually my <code>selectOneButton</code> is inside a <code>menuItem</code> which is inside a <code>splitButton</code>, when i take the selectOneButton out side the splitButton it works fine!
  why is the fact that the <code>selectOneButton</code> is inside the <code>menuItem</code> preventing it from send it to the server?
  here the code:</p>
  
  <pre><code>&lt;h:panelGroup style="float: right;" &gt; 
      &lt;h:form id="f"&gt;
          &lt;p:splitButton value="#{currentUser.fullName}" icon="ui-icon-person" styleClass="toTheRight" style="min-width: 200px;" &gt;
              &lt;p:menuitem value="Matricule: #{currentUser.matricule}"  /&gt;
              &lt;p:menuitem value="#{msgs.role}: #{currentUser.role}" /&gt;
              &lt;p:separator /&gt;
              &lt;p:menuitem&gt;
                  &lt;p:selectOneButton id="lang" value="#{currentUser.language}" valueChangeListener="#{currentUser.languageChanged}" &gt;
                      &lt;f:selectItem itemLabel="English" itemValue="en" /&gt;
                      &lt;f:selectItem itemLabel="Françcais" itemValue="fr" /&gt;
                      &lt;f:ajax event="change"/&gt;
                  &lt;/p:selectOneButton&gt;
              &lt;/p:menuitem&gt;
              &lt;p:separator /&gt;
              &lt;p:menuitem value="#{msgs.settings}" icon="ui-icon-wrench"  /&gt;
              &lt;p:menuitem value="#{msgs.logout}"  icon="ui-icon-arrowthickstop-1-w" url="/j_spring_security_logout"/&gt;
          &lt;/p:splitButton&gt;
      &lt;/h:form&gt;
  &lt;/h:panelGroup&gt;
  </code></pre>