I recently installed SLED11SP2 (Gnome) in my PD8 (on MBP15 mid2012). After fresh installation with Parallels Tools the Desktop Effects were activated and working. Now after auto updating all packets I can't activate Dekstop Effects anymore. "Desktop Effects are not supported on your current hardware / configuration. ..." The whole window movement seems a bit messy, while I move a window fringed borders appear for that window.
Just to point out, everything works and the VM is fast and stable, but this cosmetic problem is annoying.

I tried to remove and reinstall Parallels Tools. VM Graphics = 256MB with 3D Acc. activated.

It would be great to get back a clean window behaviour.