Wide lines are not supported in OS X core profile contexts.
Originally Posted by malexander
That's a good point, you do have to check the GL_LINE_WIDTH_RANGE (or GL_SMOOTH_LINE_WIDTH_RANGE, if you are using smooth lines). Both AMD and Nvidia drivers on Linux and Windows support the same aliased line ranges in the core profile as they do in the compatibility (AMD: 1 63, Nvidia: 0.5, 10). Intel graphics has a range of 1,1 (no line widths other than 1 are supported). Apple isn't known for supporting deprecated features, so they apparently set it to 1,1 as well.