>From: Marcelo de Moraes Serpa <celoserpa@gmail.com>

>> I just compiled emacs enabling carbon support  (GNU Emacs 23.1.50.1
>> (x86_64-apple-darwin10.1.1, NS apple-appkit-1038.11) of 2009-12-05) and
>> while everything seemed to work fine, the visual-bell feature is not working
>> well. I migrated all my elisp scripts from my legacy ubuntu machine and all
>> of them are loading fine :), however, the visual-bell is rendering a
>> ~100x100 square on the center of the emacs window, instead of rendering the
>> usual belts on the bottom and top of the emacs window.  For now, I just
>> disabled this feature, but I'd like to know if anyone knows why this happens
>> and how I could possibly fix it.

Marcelo, 

I can reproduce the behavior you're describing, as

   - start emacs with "Emacs -Q"
   - eval "(setq visible-bell t)"
   - do something that rings the bell

GNU Emacs 23.1.90.1 (powerpc-apple-darwin8.11.0, NS apple-appkit-824.48)
(on Mac OS X 10.4.11) rings the bell as a square in the middle of
Emacs' frame.

GNU Emacs 22.3.1 (powerpc-apple-darwin8.11.0, Carbon Version 1.6.0)
rings the bell by flashing the mode line, and the first line of the
buffer.

GNU Emacs 23.1.1 (i586-suse-linux-gnu, GTK+ Version 2.18.1)
uses the same visual bell as GNU Emacs 22.3.1 on Mac OS X 10.4.11
(flashing the mode line, and top buffer line)

The behavior of Emacs 23.1 on Mac OS X seems inconsistent with Emacs
23.1.1 on a Linux distribution, and with older (22.3) versions of
Emacs on Mac OS X.

You may want to report this with M-x report-emacs-bug.

Steve