Nils, please see if you can reproduce this on ie6. If you find something please do the initial investigation. There are no reports of this occurring on the ace/compat showcases but you might also want to double check.

If it turns out to be in the bridge then you'll need to create a new bug and link to this one under the ice project. This one needs to be address before beta.

Just saw this in the SVN timeline:
ICE-6511 Removed blockUI configuration in compat JS code since the block UI code resides solely in core. Fixed pseudo URLs used by overlay iframe to render correctly the markup.

Looks like Mircea has been all over this bug:
http://jira.icefaces.org/browse/ICE-6511

I'll do an update and test to make sure they're one and the same.

Seeing as I'm on W7, this bug required me to find a virtualized IE6 install, I tried and had some weird behaviour from "IETester" and "Utilu IE Collection". Both seem buggy and weren't fully patched versions of IE6 either. I ended up downloading the ~400mb Symantec Virtual Workspace IE package, which works great! (it better at 400mb)

http://www.symantec.com/connect/articles/virtual-internet-explorer-browser-catalog

With Mircea's update the showcase ran bug-free.

Larger problem already partially debugged by Mircea in ICE-6511