function add_plugin_action_link( $label, $url, $external = false, $priority = WP_FS__DEFAULT_PRIORITY, $key = false ) {
            $this->_logger->entrance();

            if ( ! isset( $this->_action_links[ $priority ] ) ) {
                $this->_action_links[ $priority ] = array();
            }

            if ( false === $key ) {
                $key = preg_replace( "/[^A-Za-z0-9 ]/", '', strtolower( $label ) );
            }

            $this->_action_links[ $priority ][] = array(
                'label'    => $label,
                'href'     => $url,
                'key'      => $key,
                'external' => $external
            );
        }