I closed Synaptic, and restarted it. Now when trying to get the scribus-ng RC5~1 package, I do not get the unauthenticated warning, but it says it will install libpodofo0.9.0, when I select Mark, it then still gives the error messages as before:
cribus-ng:
Depends: libjpeg62 (>=6b1) but 6b-15ubuntu1 is to be installed
Depends: libpython2.7 (>=2.7) but it is not installable
Depends: libqtcore4 (>=4:4.7.0~beta1) but 4:4.6.2-0ubuntu5.2 is to be installed
Depends: libstdc++6 (>=4.5) but 4.4.3-4ubuntu5 is to be installed