public function activateAction()
    {
        $themeId = $this->getEvent()->getRouteMatch()->getParam('themeId');
        $theme = $this->getAdminThemeService()->findById($themeId);

        $themeActivated = $this->getAdminThemeService()->findActiveThemeByArea($theme->getArea());
        if (sizeof($themeActivated) > 0) {
            $themeActivated[0]->setIsActive(false);
            $this->getAdminThemeService()->update($themeActivated[0]);
        }

        $theme->setIsActive(true);
        $this->getAdminThemeService()->update($theme);
        $this->flashMessenger()->addMessage('The theme "'.$theme->getTitle().'" is activate');

        $eventManager = new EventManager();
        $eventManager->trigger(\Zend\ModuleManager\ModuleEvent::EVENT_MERGE_CONFIG);

        return $this->redirect()->toRoute('admin/playgrounddesign_themeadmin');
    }