public function isMainZone($content)
    {
        if ($content instanceof ContentSet) {
            $pages = $this->entityManager->getRepository('BackBee\ClassContent\ContentSet')->findPagesByContent($content);

            if (count($pages) > 0) {
                foreach($pages as $page) {
                    if ($page instanceof Page) {
                        if (false !== $index = $page->getContentSet()->indexOf($content, true)) {
                            $zone = $page->getLayout()->getZone($index);
                            if (is_a($zone, '\stdClass') && 1 === $zone->mainZone) {
                                return $page;
                            }
                        }
                    }
                }
            }
        }

        return null;
    }