http://bugs.winehq.org/show_bug.cgi?id=8683
--- Comment #23 from Dmitry Timoshkov dmitry@codeweavers.com 2008-01-22 05:45:34 --- (In reply to comment #22)
Just saw the reason. in unicode, ß is 0xdf and uppercase ß (ẞ) is 0x1e9e. (I didn't even know that an uppercase ß exists - AFAIK it's not used in the german language.) Unless WoW running under Windows with the DE keyboard layout have the same bug (unlikely, since it's also sold in Germany) it seems that we found an exception to the rule that MapVirtualKeyEx always returns uppercase characters.
You can't trust Wine implementation, that's why I said that you need to write a test case to how it's supposed to behave.