Fieldsets broken with Javascript Caching

I'm not able to replicate this issue. Please try to temporarily disable potentially conflicting modules that may interfere with this functionality.

In any case, please report back about the status of this issue. Thanks.

Having the same issue here. Additionally ckeditor not showing up Admin Menu disappears and, even worse, I can't collapse or expand option fieldsets no more as I enable compression for JS.
Gonna check my modules and post here if I find any conflicts.

PS: found the same issue here: http://drupal.org/node/355741

PPS: Got it :) Admin Menu 6.x-3.0-alpha3 seems to have messed up things a little. Disabled it and everything works again. So I'm gonna roll back to a stable version of Admin Menu.

Thanks for reporting that, wentsch!
Do you know what the cause of the problem is, if it throws any errors or if it happens in more than one browser?

It happended at least in Firefox 3.6 and Chrome 4 on Windows 7 and XP.
I'm quite sure it was a cross browser issue caused by admin menu beta.
As soon as I rolled back to the latest stable version of admin menu (currently 6.x-1.5) everything worked fine again :)

Hence, a bug in admin_menu, not Wysiwyg.

Core 6.28
Wysiwyg-6.x-2.x-dev
CKEditor 4.5.3.6c70c82

"Optimize Javascript files enabled" mode gives error "ReferenceError: CKEDITOR is not defined" (it may be some other js errors).
wysiwyg.module
to find line 320 and change
- $options += array('type' => 'module', 'scope' => 'header', 'defer' => FALSE, 'cache' => TRUE, 'preprocess' => TRUE);
to
+ $options = array_merge($options, array('type' => 'module', 'scope' => 'header', 'defer' => FALSE, 'cache' => TRUE, 'preprocess' => TRUE));