Comment 10 for bug 1299223

Well, that's an upstream issue: https://bugzilla.gnome.org/show_bug.cgi?id=724732

We don't actually use the new Gtk::Stack widget that causes the problem though (as far as I know). To stop the issue from affecting Inkscape builds, we should probably stop including the full <gtkmm.h> header and only include the specific definitions that we need.

In fact, this is probably good practice anyway because it should massively reduce the size of our inclusions.