Support for GLX_ARB_framebuffer_sRGB

In OpenGL (in theory), before enabling sRGB on the window-system
framebuffer (i.e. not an FBO), you should request an “sRGB capable
visual” from GLX. While no drivers actually require this at the moment,
it’d probably be polite to implement it, just in case.

I’ve put up a patch for this (and the Win32 equivalent) at which lets you request
such a visual with SDL_GL_SetAttribute(SDL_GL_FRAMEBUFFER_SRGB_CAPABLE, 1).

Is anyone capable of testing the windows implementation (using
WGL_ARB_framebuffer_sRGB)? It probably won’t have any real effect ? I’ve
yet to see a driver which actually requires this ? but it’d be nice to
know it doesn’t crash horribly.

– David