On my system, version 1.4.3+20140219-0ubuntu2.4 of system-config-printer-gnome depended on gir1.2-gtk-3.0: installing system-config-printer-gnome/trusty-proposed pulled in gir1.2-gtk-3.0, and uninstalling gir1.2-gtk-3.0 caused the removal of system-config-printer-gnome.
On my system, version 1.4.3+20140219- 0ubuntu2. 4 of system- config- printer- gnome depended on gir1.2-gtk-3.0: installing system- config- printer- gnome/trusty- proposed pulled in gir1.2-gtk-3.0, and uninstalling gir1.2-gtk-3.0 caused the removal of system- config- printer- gnome.