title: how to refresh referenced part of page with prime faces' p:commandLink?
body: <p><em><strong>Environment: Tomcat 6 ,jsf 2.0,prime faces 2.2.1 ,chrome explorer</em></strong></p>
  
  <p>I want to click the "ViewDetail" link in the left expanded tree and show the product's detail info. But the code below didn't work.
  Then I add the attribute ajax="false" to the link, it seems work. But the "p:treeTable" which lies on left part of the page is
  also refreshed and collapsed. So how can I do for this: click the link on the left expanded tree node, show the info on the right part
  of the page,and keep the left expanded tree node still expanded.</p>
  
  <pre><code>&lt;h:form id="BizTypeTreeTableForm" &gt;
          &lt;p:layout fullPage="true"&gt;
              &lt;p:layoutUnit id="left" position="left" scrollable="true"     width="350" resizable="true" closable="false" collapsible="true" minWidth="250" &gt;
                    &lt;p:treeTable id="BizTypeTreeTable" value="#    {treeTableController.root}" var="treeTable"&gt;
                        &lt;p:column&gt;
                                &lt;f:facet name="header"&gt;ProductName&lt;/f:facet&gt;
                                &lt;h:outputText value="#{treeTable.TYPENAME.value }" /&gt;
                            &lt;/p:column&gt;
                            &lt;p:column style="width:5%"&gt;
                                &lt;f:facet name="header"&gt;Action&lt;/f:facet&gt;
                                &lt;p:commandLink value="ViewDetail" update="content"      action="#{treeTableController.showDetail}"&gt;
                                &lt;/p:commandLink&gt;
                        &lt;/p:column&gt;
                        &lt;/p:treeTable&gt;
              &lt;/p:layoutUnit&gt;
              &lt;p:layoutUnit id="center" rendered="true" position="center"    style="text-align:left;" scrollable="true" &gt;
                  &lt;h:outputText value="Please click the left tree node" rendered="#    {allTabManager.productObject.TypeNo.value eq null}"/&gt;
              &lt;div id="content" class="ui-widget"&gt;
                      &lt;div class="post"&gt;
                      &lt;ui:insert name="content_tab" &gt;...&lt;/ui:insert&gt;
                  &lt;/div&gt;
                  &lt;/div&gt;
              &lt;/p:layoutUnit&gt;
           &lt;/p:layout&gt;
      &lt;/h:form&gt;
  </code></pre>