It's simply not necessary anymore. At least 3.1.5 build and works just fine on a system without orbit here. The config file still references it, but not as a dependency, so I guess it can be safely removed. Reproducible: Always
gnome-git/gtkhtml $ grep -ri orbit * configure.ac:ORBIT_IDL="`$PKG_CONFIG --variable=orbit_idl ORBit-2.0`" configure.ac:AC_SUBST(ORBIT_IDL) gnome-git/gtkhtml $ You're right. I've removed the orbit dependency from gtkhtml in both master and gnome-next branches of the overlay.