Advanced options fieldset is inaccessible during install

It appears this problem started with CVS commit 256032 for issue 505084.

The same problem happens on Safari 4.0.3 and likely other browsers too. A temporary work-around is to disable Javascript. The fieldsets will all be open with nothing collapsing.

It appears that the problem was introduced with this revision to includes/form.inc:
$Id: form.inc,v 1.366 2009/08/25 21:16:31 webchick Exp $

Version 1.365 of form.inc works fine, while version 1.366 fails. To isolate the time of the problem, run cvs up -D "2009.08.25.21.16.00" and you'll find that it works, but update your repository to one minute later, cvs up -D "2009.08.25.21.17.00", and you'll find that it fails.

This line of code at line 1597 in -r 1.365 of form.inc works:
drupal_add_js('misc/collapse.js');

Whereas the revised line 1597 in 1.366 fails:
$element['#attached_js']['misc/collapse.js'] = array();

I'll post on that issue thread to let them know and see if we can track this down. Thanks for reporting this!

This is still true for the download dated 8/28, and I can confirm it's true in IE8 as well.

See #560944: move collapsible fieldset logic from theme_fieldset hook to form_process_fieldset

Yes, and #560944: move collapsible fieldset logic from theme_fieldset hook to form_process_fieldset includes a simple patch to fix this behavior.

Hitting the subscribe button!

Marking fixed. This is fixed in HEAD: #560944: move collapsible fieldset logic from theme_fieldset hook to form_process_fieldset.