title: Primefaces p:dialog doesn't always show up if update="dlg" in commandButton
body: <p>I have a jsf facelet page like this (extremely simplified version): </p>
  
  <pre><code>    &lt;h:form id="frmAnagPersonName"&gt;
          &lt;p:commandButton value="Edit" icon="ui-icon-gear" 
                           update="@form :frmEdit"
                           onsuccess="_dlgEdit.show()"/&gt;
          ...
          &lt;p:dataTable etc...
          ...
  
  
      &lt;/h:form&gt;
  
      &lt;p:dialog id="dlgEdit" widgetVar="_dlgEdit" dynamic="true" modal="true" closable="true"
                header="Person Identity"&gt;  
          &lt;h:form id="frmEdit" &gt;
              &lt;p:panelGrid id="pnlEdit" columns="2"&gt;
                  &lt;p:outputLabel id="lblName" for="eName" value="Name"/&gt;
                  &lt;p:inputText id="eName" value="#myBean.personName}"
              &lt;/p:panelGrid&gt;
          &lt;/h:form&gt;
      &lt;/p:dialog&gt;  
  </code></pre>
  
  <p>It works fine, until I put a dynamyc Header in the dialog: </p>
  
  <pre><code>&lt;p:dialog ... header="#{myBean.header}" ...  &gt;  
  </code></pre>
  
  <p>at which point i have to change the <code>update</code> attribute in the <code>p:commandButton</code>: </p>
  
  <pre><code>update="@form :dlgEdit"  
  </code></pre>
  
  <p>But in this case the dialog will show up only at the first click on the button. It won't show up the second time, then again show up...<br>
  Why? How can I have the dialog show up always?</p>
  
  <p>Thank you</p>