http://bugs.winehq.org/show_bug.cgi?id=16126
--- Comment #14 from el elton@schiert.net 2009-01-09 23:44:04 --- Created an attachment (id=18606) --> (http://bugs.winehq.org/attachment.cgi?id=18606) patch to modify main_key_DE_nodead_105 layout
OK, I tested all the german layouts one by one and found out which one breaks it for me; it was main_key_DE_nodead_105.
In keyboard.c there is a comment saying "Remember that your 102nd key (to the right of l-shift) should be on a separate line, see existing tables". The aforementioned layout is the only german one that did not have the "<>" key on an extra line.
I moved this key to it's own line and now it's working.