@stof thank you very much for you time. the reason I need property parent is because I have a sophisticated field type (kinda collection of entities the main idea of which is to link entities received and those stored in DB by using ID of entities), because it is not possible with existing collection type, which uses ordinal position, so the reason is - I need to attach my event handler on the root form.
with Symfony 2.2 I get root-form this way:
```
        $rootFormBuilder = $builder;
        while ($rootFormBuilder->hasParent()) {
            $rootFormBuilder = $rootFormBuilder->getParent();
        }
        $subscriber = new IdBasedCollectionFormErrorKeyFixerListener($builder);
        $rootFormBuilder->addEventSubscriber($subscriber);
```
full listing https://gist.github.com/tiger-seo/67a6e8e7177b3b6c104d