Comment 9 for bug 1072828

It took a little time to figure out how to bring up the window manually, but here it is, to reproduce, run:

sudo python3 /usr/lib/python3/dist-packages/DistUpgrade/dist-upgrade.py --partial --frontend=DistUpgradeViewGtk3 --datadir=/usr/share/ubuntu-release-upgrader/

on Quantal. The attached screen, or something similar should show up, if there are packages to upgrade.