title: Update component before actionListener finish
body: <p>I have a dialog, when user press the button 'Accept' I want to show a ProgressBar in the same dialog, but this its update when actionListener finish.</p>
  
  <pre><code>&lt;p:dialog id="dlgGenerarLista" modal="true" height="180" width="500" header="Generar Lista de Trabajo" widgetVar="dlgGenerarLista"&gt;
      &lt;p:commandButton onclick="PF('dlgGenerarLista').hide();" value="Cancel" /&gt;
      &lt;p:commandButton id="btnAceptarGenerar" value="Accept"
      actionListener="#{crearEstrategiaBeans.GenerarListaTrabajo}"
      oncomplete="PF('dlgGenerarLista').hide();"update="basic"/&gt; 
      &lt;p:panel id="basic" widgetVar="basic"&gt;                 
          &lt;p:progressBar rendered="#{crearEstrategiaBeans.visibilidadBarraProgreso}" id="progressBarIndeterminate"  mode="indeterminate"/&gt;
      &lt;/p:panel&gt;   
  &lt;/p:dialog&gt;
  </code></pre>
  
  <p>In the method <em>GenerarListaTrabajo()</em> I say that <em>visibilidadBarraProgreso = "true"</em> , so I want that in that moment it shows the progressBar. The progresBar it show when all the process finish.  </p>