When I add
NSOpenGLPFAMultisample,
NSOpenGLPFASampleBuffers, 1,
NSOpenGLPFASamples, 2,
to my pixel format, it doesn't work on an NVIDIA GeForce 6800.
The card has GL_ARB_multisample, Max Samples = 4
and 256 MB VRAM, so it "should" work. When I remove those 3 lines above and just set the following pixel format, it works. What do I miss?

NSOpenGLPixelFormatAttribute attribs[] =
{
NSOpenGLPFANoRecovery,
NSOpenGLPFAWindow,
NSOpenGLPFAAccelerated,
NSOpenGLPFADoubleBuffer,
NSOpenGLPFAColorSize, 32,
NSOpenGLPFAAlphaSize, 8,
NSOpenGLPFADepthSize, 24,
NSOpenGLPFAMultisample,
NSOpenGLPFASampleBuffers, 1,
NSOpenGLPFASamples, 2,
NSOpenGLPFAAccumSize, 64,
NSOpenGLPFASingleRenderer,
NSOpenGLPFAScreenMask,
CGDisplayIDToOpenGLDisplayMask(kCGDirectMainDisplay),
0
};

Lorenzo

Tried taking out the accum and/or setting ColorSize to 24? Those are the only peculiar things I see in that list.