http://www.smnlikdat.org/project.php?issueid=16#note38
I modified the new conditional with $tabcategories to include your parenthesis fix
PHP Code:
<if condition="(THIS_SCRIPT == 'indexTAB' AND (in_array($forum['forumid'], $tabcategories) OR in_array('all', $tabcategories))) OR (THIS_SCRIPT == 'forumdisplay')">
and like you said, no more errors in the template manager or forums page, but tabindex.php returns the error with the patch.