For Ubuntu 9.04, update-notifier behavior was changed such that update-manager will be automatically launched on a regular basis, but behind other applications.
It does this by launching "update-manager --no-focus-on-map". On standard Ubuntu (using metacity), this behavior works properly.
You can manually verify by running that command in a terminal.
On Xubuntu & Mythbuntu (using xfwm4), the update manager window pops up above your running application.
Binary package hint: xfwm4
For Ubuntu 9.04, update-notifier behavior was changed such that update-manager will be automatically launched on a regular basis, but behind other applications.
It does this by launching "update-manager --no-focus-on-map". On standard Ubuntu (using metacity), this behavior works properly.
You can manually verify by running that command in a terminal.
On Xubuntu & Mythbuntu (using xfwm4), the update manager window pops up above your running application.