I don't know where at your site, but you can see it on mine. If you go there:
http://blackdaemon.no-ip.org/wiki/dokuwiki
...you can see the outliner plugin working (click on "DokuWiki resources"). It uses onclick handler.
Then try to highlight something:
http://blackdaemon.no-ip.org/wiki/dokuwiki?s=definitions
plugin stops working because onclick="somefunction('param')" will be replaced with onclick="somefunction(\\'param\\')".
More detail to this is here:
http://cz2.php.net/preg_replace
See comment made by Tim K., on 28-Apr-2005 09:27