function has_installed_addons() {
            if ( ! $this->has_addons() ) {
                return false;
            }

            foreach ( self::$_instances as $instance ) {
                if ( $instance->is_addon() && is_object( $instance->_parent_plugin ) ) {
                    if ( $this->_plugin->id == $instance->_parent_plugin->id ) {
                        return true;
                    }
                }
            }

            return false;
        }