This breaks the GNOME update since gtkmm2 2.18.1 required gtk+2 2.17+:
...
checking for GDKMM... configure: error: Package requirements (giomm-2.4
>= 2.21.2 pangomm-1.4 >= 2.25.1.3 gtk+-2.0 >= 2.17.11) were not met:
Requested 'gtk+-2.0 >= 2.17.11' but version of GTK+ is 2.16.6
We have this version, but it is the devel version of gtk+2. I don't
think people want to use a devel branch of something as crucial to the
rest of their system as GTK.