I'm trying to have Ubuntu 15.10 to work in coherence mode. When I try to activate it, it pops an error dialog box telling me to disable visual effects with a link (to a wrong KB article) http://kb.parallels.com/111474 . I have found what seems to be the right instructions at http://kb.parallels.com/en/111510 and did so. I installed the gnome-session-flashback package. Shut down the VM and restarted it, and selected the Gnome (megacity) option from the drop-down menu before logging in. But, when I try to activate coherence then. I get the same error message as before. Thanks for your help.
An update was featured to fix the problem. You actually have to not use the metacity fallback for it to work. The second KB article is giving outdated information.