I will soon release gtkmm 2.24.0. This one should really be the last release of the gtkmm-2.4 API, give or take some minor bug-fixes. Afterwards, we can focus completely on gtkmm 3.
So this is your last chance to mention problems that we should fix in the gtkmm-2.4 API. Remember that it’s just meant to help you prepare for porting to gtkmm 3 so we’ve added as much of the new API as possible to gtkmm-2.4, but tell us if we missed something.
I already have gtkmm-documentation and glom building in branches with gtkmm 2.23/24 with no use of deprecated API.