The lightweight launcher currently relies on gnome2 libraries and needs an older version of ubuntu to run at the moment. We are working on converting it to gnome3 (which ubermix 2 is based on) so that it can be an option for verision 2 and up, however it is still a bit too buggy in its current state to be of any use. ubermix 1 is still a viable option, so if you prefer the launcher I'd use it for now, and stay tuned for an update in the future.