Refresh Rate In Full-screen Mode

I use 1.5 ALPHA 4

How does it work ? It seems the “frame-rate” button doesn’t change anything. It’s still in 60 Hz when I switch to full-screen. And it hurts my eyes and head really bad since I have a 22" :) Is it a bug or is there a way to make it take effect ?

Thanks for the help,
Nino