http://bugs.winehq.org/show_bug.cgi?id=12527
--- Comment #1 from Reece Dunn msclrhd@gmail.com 2008-04-12 04:11:50 --- Disregard the comments relating to steps [8] and [11], as that behaviour is observable on Windows as well. It looks as if WinMerge isn't setting the WS_GROUP style correctly.
The other issues still stand, though.