public function configure()
 {
     unset($this['sf_guard_user_group_list']);
     $this->setWidget('sf_guard_group_permission_list', new sfWidgetFormSelectDoubleList(array('choices' => sfGuardPermissionPeer::getChoices(), 'label_unassociated' => 'No seleccionados', 'label_associated' => 'Seleccionados', 'associate' => '<img src="../../../sfFormExtraPlugin/images/next.png" alt="Seleccionar" />', 'unassociate' => '<img src="../../../sfFormExtraPlugin/images/previous.png" alt="Deseleccionar" />')));
     $this->widgetSchema['sf_guard_group_permission_list']->setLabel('Permissions');
 }