@Override
 public void execute(Event<UIDocActivityComposer> event) throws Exception {
   UIDocActivityComposer docActivityComposer = event.getSource();
   PopupContainer popupContainer =
       docActivityComposer
           .getAncestorOfType(UIPortletApplication.class)
           .findFirstComponentOfType(PopupContainer.class);
   popupContainer.activate(UIDocActivitySelector.class, 500, POPUP_COMPOSER);
   event.getRequestContext().addUIComponentToUpdateByAjax(popupContainer);
 }
 @Override
 public void execute(Event<UIDocActivityComposer> event) throws Exception {
   final UIDocActivityComposer docActivityComposer = event.getSource();
   // Reset values
   docActivityComposer.resetValues();
 }