http://bugs.winehq.org/show_bug.cgi?id=35718
--- Comment #63 from Gediminas Jakutis gediminas@varciai.lt --- (In reply to Yuri Shishenko from comment #62)
Are You sure the black screen isn't present before changing the refresh rate? Because, currently, it is supposed to create two "windows" for fullscreen games/programs and render to the 2nd one while the first window is simply black. It puts the 2nd window to the foreground, so normally this should not be noticed.