title: Primefaces ConfirmDialog not vertically centered in form updated with ajax
body: <p>I have a form that "grows" through Ajax+Rendered when some operations are clicked. The problem is that my p:confirmDialog is not vertically centered when the form grows. When in "normal size", the dialog is correctly centered.</p>
  
  <p>I have already tried:</p>
  
  <ul>
  <li>Remove or add "appendToBody" attribute</li>
  <li>Change the position of the declaration in the page (before and after h:form)</li>
  <li>Overwrite the "Top" in CSS</li>
  </ul>
  
  <p>Is that an issue from Primefaces (currently using v4) or am I doing something wrong? Since I use lots of "rendered" attributes, should I "rerender" the dialog?</p>
  
  <p>Here follows a snippet of my code.</p>
  
  <pre><code>&lt;h:form id="myForm"&gt;            
      &lt;p:fieldset legend="Hello"&gt;
          &lt;!-- lots of things here --&gt;
      &lt;/p:fieldset&gt;
      &lt;p:spacer height="20px" /&gt;
      &lt;p:fieldset legend="Dashboard" 
          id="thisOneMakesTheFormGrows" 
          rendered="#{bean.include or bean.edit}"&gt;
          &lt;!-- this one has lots of items, making the page grow when the 'rendered' attribute is true --&gt;
      &lt;/p:fieldset&gt;
  &lt;/h:form&gt;           
  
  &lt;p:confirmDialog global="true"
      id="meuConfirmDlg"
      appendToBody="true"
      showEffect="fade"
      width="500px" 
      hideEffect="fade"
      widgetVar="confirmDlg"
      closable="false"&gt;
      &lt;p:commandButton value="Yes" type="button" styleClass="ui-confirmdialog-yes" icon="ui-icon-check" /&gt;
      &lt;p:commandButton value="No" type="button" styleClass="ui-confirmdialog-no" icon="ui-icon-close" /&gt;
  &lt;/p:confirmDialog&gt;
  </code></pre>