public function unused()
    {
        $ids = [];
        foreach ([$this->inFrontTheme(), $this->inBackTheme()] as $bundle) {
            foreach ($bundle as $region => $blocks) {
                foreach ($blocks as $block) {
                    $ids[] = $block->get('id');
                }
            }
        }

        $notIn = array_unique($ids);
        $notIn = empty($notIn) ? ['0'] : $notIn;

        return $this->find()
            ->where([
                'OR' => [
                    'Blocks.id NOT IN' => $notIn,
                    'Blocks.status' => 0,
                ]
            ])
            ->all()
            ->filter(function ($block) {
                return $block->renderable();
            });
    }