http://bugs.winehq.org/show_bug.cgi?id=7712
------- Additional Comments From rmay@ou.edu 2007-16-03 12:08 ------- This may or may not be pertinent: "The character set of a window is determined by the use of the RegisterClass function. If the window class was registered with the ANSI version of RegisterClass (RegisterClassA), the character set of the window is ANSI. If the window class was registered with the Unicode version of RegisterClass (RegisterClassW), the character set of the window is Unicode."
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winui/winui...
This to me suggests that Windows bases the A/W on the RegisterClassA/W called rather than the CreateWindowA/W called.