Ok, so because there wasn't any Ubuntu dev giving any attention to this bug, I decided to report it upstream myself. I just added a remote bug watch. Within a few hours I already got a reply on my bugreport, the bug is apparantly not X.org's fault, but Ubuntu's fault. I can imagine that the Ubuntu dev's are busy, but I'm a bit disappointed that nothing has been done on this serious bug for quite a few months.
-- X.org doesn't detect widescreen resolution https://launchpad.net/bugs/63551 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs