http://bugs.winehq.org/show_bug.cgi?id=26761
--- Comment #3 from Bruno Jesus 00cpxxx@gmail.com 2013-10-04 22:05:02 CDT --- The function was improved by [1]. That is why you see "Workgroup", it's hardcoded.
I'm not sure a workgroup makes sense outside of samba.
[1] - http://source.winehq.org/git/wine.git/commitdiff/ed28cab62488d58a8e2d6d4c675...