Experimental 219b4b8, though I also observed this behavior in older experimentals.
SDL, Windows 8.
Err, yeah. This is a weird one. So I was playing Cata late last night and turned my screen backlight brightness way down while Cata was running. When I closed it, though, the brightness went back up to maximum. Now when I opened it again it turned the brightness back down to zero.
Maybe it’s an OpenGL context thing or something? Really weird. Anyone else get this?