public function disablePlugin($id, $isUser = false)
    {
        $code = $this->getIdentifier($id);
        if (array_key_exists($code, $this->disabledPlugins)) {
            return false;
        }

        $this->disabledPlugins[$code] = $isUser;
        $this->writeDisabled();

        if ($pluginObj = $this->findByIdentifier($code)) {
            $pluginObj->disabled = true;
        }

        return true;
    }