code: private void setBlocking(boolean blocking) {
  
          if (blocking) {
              getElement().addClassName(I_CmsLayoutBundle.INSTANCE.notificationCss().blocking());
          } else {
              getElement().removeClassName(I_CmsLayoutBundle.INSTANCE.notificationCss().blocking());
          }
      }
docs: Toggles the blocking overlay.<p>
  
  @param blocking <code>true</code> to show the blocking overlay