Attached is a diff I've done that seems to fix the issue for me. I've squeezed the patches from Gnome bug 128983 into the source from 6.06. Not sure if it's 100% correct, but may help others who are suffering from misaligned project plans.
** Attachment added: "Frankenpatch of diffs in Gnome bugzilla #128983" http://librarian.launchpad.net/4685187/planner.diff -- (Breezy) Planner Gantt view vertically misaligned https://launchpad.net/bugs/24281 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs