Vertical retrace syncing with X

[Meghazi Fabien]

Does X.org allows to get vertical retrace syncing ?
I asked in xmame mailing list why games using scrollings where rendered with 
ugly lines due to frames half-rendered as if there was no double buffering. I 
was told that there was no reliable way to use the vertical retrace sync 
under X. So I wonder to know if X.org will face this problem or not.

Thanks.

-- 
Fabien Meghazi