After recent upgrade to xorg-server-1.6, etc-proposal's qt4 frontend stopped highlighting changes in diff view with background color (there is neutral gray color everywhere, so it's not possible to easy recognize old and new lines of config). There is no error printed in command line.
Not sure which lib is responsible, but before upgrade everything was ok. Already tried emerge -e etc-proposals to rebuild all dependencies with no effect.
Unfortunately there is currently no one maintaining the qt front end. If you or any one else can update it. That would be great.
Qt4 was removed from tree altogether so this is probably obsolete until someone decides to pick up the work and port it to PyQt5.