[update-manager] Main window inaccessible when and error message box happens

On Ubuntu HH, I was making a dist upgrade with update-manager, an error happens (on flashplugin-nonfree, but without importance for the current problem).
Error message was (french) :
Abandon de la mise à jour. Votre système est peut-être inutilisable. Une récupération va être lancée (dpkg --configure -a).
==> which can be translated as "Update abort. Your system may be unusable. A recovery will be launched (dpkg --configure -a)"

And the problem : If I want to access main update terminal window (with terminal rolled out), main windows cannot be accessed - I can't use the right slider, or copy/paste the text. The whole process is locked by the error box.

If I click the box's OK button, a message happens in the main window. And the process ends quick, without letting the user see the messages.

My asking : Have the main window still open to let the user access the messages before quitting.

I know the log is in /var/log/dist-upgrade/apt-term.log but common user will have hard time to figure what happens.

PS: upd-mgr version = 1:0.87.2 (maybe AFTER the upgrade)