From the release notes:
Originally Posted by d2kx
So, there maybe some problem for certain situation. However, interestingly, I manage to enable both Composite + DRI (for the first time)!
Corruption may be observed with certain applications on some Linux distributions which enable the Composite extension by default, e.g., RHEL 5. If you are observing application corruption, please disable the Composite extension. Further details can be found in topic number 737-28224
So far, no problem yet...
# grep Composite /var/log/Xorg.0.log
(**) Extension "Composite" is enabled
# grep DRI /var/log/Xorg.0.log
(II) Loading extension XFree86-DRI
(**) fglrx(0): Option "NoDRI" "no"
(**) fglrx(0): NoDRI = NO
(II) Loading extension ATIFGLRXDRI
(II) fglrx(0): doing DRIScreenInit
(II) fglrx(0): DRIScreenInit done
(II) fglrx(0): DRI initialization successfull!
(II) fglrx(0): [DRI] installation complete
EDIT: Unfortunately, if I run xcompmgr -c, I got a lot of screen corruption (as stated in the release notes). So, even though I can enable it in the xorg.conf, it is still not usable. But, I guess this can be reason to be hopeful. Maybe the next release will be better.