Reply To: Open confirmation required message in a lightbox

I found in the subscription.php the right lines and changed them. Though it is still not working and loads in a new window.

 // Is there a custom url?
        if (!empty($this->options[$key . '_url'])) {
           echo '<iframe src="' . self::add_qs($this->options[$key . '_url'], 'nk=' . $user->id . '-' . $user->token, false) . $params . '"></iframe>';
            die();
        }