In der Baumstruktur von Beitrag zu Beitrag springen - wie?

Code:
$plugins->add_hook('showthread_threaded', 'syncom_showthread_threaded');



function syncom_buildtree(&$threadtree, $replyto=0)

{

        global $tree;



        if(is_array($tree[$replyto])) {

                foreach($tree[$replyto] as $key => $post) {

                        $threadtree[] = $post['pid'];



                        if($tree[$post['pid']])

                                syncom_buildtree($threadtree, $post['pid']);

                }

        }

}



function syncom_showthread_threaded()

{

        global $posts, $mybb;



        $threadtree = array();

        syncom_buildtree($threadtree);

        $post = array_search($mybb->input['pid'], $threadtree);



        $previouspost = 0;

        $nextpost = 0;



        if ($post > 0)

                $previouspost = $threadtree[$post-1];



        if ($post < sizeof($threadtree))

                $nextpost = $threadtree[$post+1];



        if ($previouspost > 0)

                $output = '<strong><a href="showthread.php?tid='.$mybb->input['tid'].'&pid='.$previouspost.'&mode=threaded">&laquo; Ein Beitrag zur&uuml;ck</a> | </strong>';

        else

                $output = '&laquo; Ein Beitrag zur&uuml;ck <strong>|</strong>';



        if ($nextpost > 0)

                $output .= '<strong><a href="showthread.php?tid='.$mybb->input['tid'].'&pid='.$nextpost.'&mode=threaded">Ein Beitrag vor &raquo;</a></strong> ';

        else

                $output .= 'Ein Beitrag vor &raquo;';



        $posts = str_replace('<div class="float_left smalltext">',

                                '<div class="float_left smalltext">'.$output.' <strong>|</strong> ',

                                $posts);



        $posts = str_replace('<div class="author_buttons float_left">',

                                '<div class="author_buttons float_left">'.$output,

                                $posts);

}