public function canAddblock()
    {
        if (!$this->actor) {
            return false;
        }

        if (!$this->getItem()) {
            return false;
        }

        if ($this->getItem()->isAdministrable() && !$this->canAdminister()) {
            return false;
        }

        return $this->actor->authorize('blocker', array('viewer' => $this->getItem()));
    }