There seems to be a problem with seven_fieldset function in the template.php

The /node/add/page gives me a white screen of death and the module listing page gives me the following warning (9, one per fieldset) :

warning: preg_match() expects parameter 2 to be string, array given in /Users/antoine/versioned/asobo/public_html/includes/bootstrap.inc on line 777.

The problem seems to be related to some code written to handle the fielsets.

Trying Seven under a drupal-6.14 install with cck,views and company, but I would think this is not related to other installed modules. (of course if needed I can provide a more extensive setup info)

I'm sorry I can't solve the problem (and suggest a patch), but I've pinpointed the problem to the following code (removing it solves the warnings and page add error, but leaves all the fielsets uncolapsible)

"template.php - line 83-89"

    if (!isset($element['#attributes']['class'])) {
      $element['#attributes']['class'] = array();
    }
    $element['#attributes']['class'][] = 'collapsible';
    if (!empty($element['#collapsed'])) {
      $element['#attributes']['class'][] = 'collapsed';
    }