http://bugs.winehq.org/show_bug.cgi?id=5884
--- Comment #13 from Jiri Palecek jpalecek@web.de 2007-12-01 05:36:09 --- I'm pretty sure you got the calculation wrong. The whole thing is, if you pass 1 as iFirstDay, the first day of week is sunday as in US; if you pass 0 and read 0 from the locale, it is _monday_. (don't ask me why...)
test does not check the returned values to match any (hardcoded) values
which is why your test can't check this, you can try it with this test http://www.nabble.com/olaut32:-VarWeekdayName-test-t4209794.html
It checks the names against what is read from the locale, so it should work under any locale.