title: How <p:dialog>'s position remain center of a page after increasing its size dynamically?
body: <p>In my application I have a <code>&lt;p:dialog&gt;</code>, in the dialog I placed a <code>h:selectBooleanCheckbox</code> . If this is checked then one row below this will apear otherwise 
  this row will hidden.By default dialog's position is center of the page. Now Problem is when I checked this <code>booleanCheckbox</code> the height and width of dialog is 
  increased as new row's content is greater than previous <code>dialog</code> , then the position doesn't remain center of the page, I mean the dialog's size increases bottom and right side.
  How I can display dialog at center after increasing its content? Any pointer will be very helpful to me .   Thanks,</p>
  
  <p>Sory for my bad English.</p>
  
  <p>code of .xhtml is given below:</p>
  
  <pre><code>&lt;p:dialog id="popUp" widgetVar="popUpWidget"
    showEffect="fade" hideEffect="explode" resizable="false" modal="true"&gt;
      &lt;p:row&gt;
          &lt;h:outputLabel value="#{adbBundle['addRemoveActivityManagers']}" /&gt;
          &lt;h:selectBooleanCheckbox value="#{activityListController.editActivityManager}" immediate="true"&gt;
              &lt;p:ajax event="click" update="adminPanel" listener="#{activityListController.updateActivityManager}"/&gt;
          &lt;/h:selectBooleanCheckbox&gt;
      &lt;/p:row&gt;
      &lt;p:row rendered="#{activityListController.editActivityManager}"&gt;
          &lt;p:column&gt;
              &lt;p:dataTable id="sourceManagerDataTable" value="#{activityListController.activitySourceUsers}" var="manager" liveScroll="true" scrollRows="5" 
                  scrollHeight="125" selection="#{activityListController.selectedActivitySourceUsers}" selectionMode="multiple"
                  filteredValue="#{activityListController.filteredSourceUsers}" scrollable="true" styleClass="activityManager"&gt;
                  &lt;f:facet name="header"&gt;
                      &lt;h:outputText value="Available Managers" /&gt;
                  &lt;/f:facet&gt;
                  &lt;p:column headerText="Full Name" sortBy="#{manager.lastName}" filterBy="#{manager.fullName}" filterMatchMode="contains"&gt;
                      &lt;h:outputText value="#{manager.lastName}, #{manager.firstName}" /&gt;
                  &lt;/p:column&gt;
              &lt;/p:dataTable&gt;
          &lt;/p:column&gt;
      &lt;/p:row&gt;&lt;/p:dialog&gt;
  </code></pre>