Hi, the Qt graphics plugin in Navit is currently unmaintained, so it's probably best to drop it from the Debian package - it's barely usable at the moment.
Once it starts being maintained, it will probably be migrated to Qt 5. Greetings Sebastian Leske P.S. You forwarded this bug to the GitHub issue tracker, which was only enabled temporarily by mistake. Navit bugs should be reported to http://trac.navit-project.org/ . Thanks!