public function allowComponent($role, $componentClass, $privilege = null)
    {
        if ($privilege) throw new Kwf_Exception("Not yet implemented");
        if (!is_null($role)) $role = $this->_roleRegistry->get($role);
        $rules =& $this->_getRules('Component', $componentClass, $role, true);
        $rules['type'] = Kwf_Acl::TYPE_ALLOW;
        return $this;
    }