Can't turn off line anti-aliasing - v19.0p

[R Reynolds]

I've finally replaced my 10+ year old computer with something more up to date. It runs A:M just fine and solves two minor but annoying problems A:M had with my old hardware. But now I can't turn off spline anti-aliasing. Checking the "Antialias Lines" box has no effect. I've set the Radeon software Anti-Aliasing switch to "Use application settings".  

This isn't even close to being a real problem and I'll probably get used to it with time but Steffen might want to look into it. Maybe it's a symptom of other driver issues or maybe I'm just missing something.