IFAIK compiz can manage workspaces (like metacity) and viewport. If the pager show only a gray rectangle, viewports are enabled (and you should have the cube) but in this case you can't do things like move windows between viewports.
-- [compiz] Cube does not work https://launchpad.net/bugs/82957 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
