title: Method is not called once uncheck all is clicked
body: <p>I need your assistant in calling a method once the user clicks on the Unselect All checkbox which is located at the top of the dataTable. The dataTable code is:</p>
  
  <pre><code>&lt;p:dataTable id="PendingRequests" var="hr" selection="#{hrdirector.selectedRequests}"
               value="#{hrd.listPendingRequests}"  rowKey="#{hr.requestNo}"
               paginatorTemplate="{RowsPerPageDropdown} {FirstPageLink} {PreviousPageLink} {CurrentPageReport} {NextPageLink} {LastPageLink}"
               rowsPerPageTemplate="5,10,15" paginatorPosition="bottom"
               filteredValue="#{hrd.filteredRequests}" widgetVar="dataTableWidgetVar"
               emptyMessage="No Requests are available to be displayed"&gt;
               &lt;p:ajax event="toggleSelect" listener="#{hrdirector.ShowTotalSelectAll}" process="@this"
                                  update="@form"/&gt;
  </code></pre>
  
  <p></p>
  
  <p>And the code in the method ShowTotalSelectAll is:</p>
  
  <pre><code>public void ShowTotalSelectAll() {
  if (selectedRequests.size() &gt; 0 || selectedRequests != null)
  {
  // do some actions
  else {
  System.out.println("UnSelect All");
  </code></pre>
  
  <p>// update total
      }
      }
  The above code will work only in case of the Select All, however when the user clicks again to Unselect, the method will not be called.</p>