I ran into the same problem. Update-manager should at least use apt.conf proxy settings and then we can give users a APT-proxy gui tool.
A workaround is to run "gksu gnome-network-preferences". We could add a network preferences icon to the System --> Administration menu that points to "gksu gnome-network-preferences" and label the icon as "Network Proxy (root)"
I ran into the same problem. Update-manager should at least use apt.conf proxy settings and then we can give users a APT-proxy gui tool.
A workaround is to run "gksu gnome-network- preferences" . We could add a network preferences icon to the System --> Administration menu that points to "gksu gnome-network- preferences" and label the icon as "Network Proxy (root)"