Comment 3 for bug 1174411

However, looking at debain/control, checkbox doesn't suggest or recommend gksu. it is a dependency by checkbox-gtk, but not by checkbox-qt:

Package: checkbox-gtk
Section: gnome
Architecture: all
Depends: checkbox (>= ${source:Version}),
         gir1.2-gtk-3.0,
         gksu,
         python3-gi,
         python3-gi-cairo,
         ${misc:Depends}
Description: GTK interface for checkbox
 This project provides an extensible interface for system testing. The
 results can then be sent to Launchpad.
 .
 This package provides a GTK interface for answering tests.

Package: checkbox-qt
Architecture: any
Depends: checkbox (>= ${source:Version}),
         libqt4-dbus,
         libqtgui4,
         python3-dbus,
         ${misc:Depends},
         ${shlibs:Depends}
Description: QT4 interface for checkbox
 This project provides an extensible interface for system testing. The
 results can then be sent to Launchpad.
 .
 This package provides a QT4 interface for answering tests.

So perhaps what needs to happen, assuming that A: gksu is still in Main, but NOT part of the base install for Ubuntu Desktop and B: because of this we never noticed it when installing checkbox-qt, we need to make gksu a dependency for checkbox-qt as well.

Time to fire up vbox and do an install to investigate.