Same problem exist for libgtk2.0-0:
~$ apt-cache policy libgtk2.0-0 libgtk-3-0
libgtk2.0-0:
Installed: 2.24.23-0ubuntu1.1
Candidate: 2.24.23-0ubuntu1.1
Version table:
*** 2.24.23-0ubuntu1.1 0
100 /var/lib/dpkg/status
2.24.23-0ubuntu1 0
500 http://mirror.fsf.org/trisquel/ belenos/main i386 Packages
libgtk-3-0:
Installed: 3.10.8-0ubuntu1.2
Candidate: 3.10.8-0ubuntu1.2
Version table:
*** 3.10.8-0ubuntu1.2 0
100 /var/lib/dpkg/status
3.10.8-0ubuntu1 0
500 http://mirror.fsf.org/trisquel/ belenos/main i386 Packages
Here you can see that pre-installed version differs from that of available on
repository! (you can check difference between this link (pre-installed list
with version) and from this link (packages for belenos on repository)
Note: I've not done any dist-upgrade, This is (clean) installed Trisquel 7.0