Please update gtkmm24 in rawhide to latest unstable version 2.21.1.
gtkmm24 used to bundle atkmm, but it was split out to a separate package in gtkmm-2.21.1 to make gtkmm24 and gtkmm30 parallel installable.
I've packaged up new atkmm and added you as comaintainer; please build gtkmm24-2.21.1 against the new atkmm-devel.
I had to untag atkmm from dist-f14 as it was breaking buildroots. This means that you'll need to tag atkmm again when you are building newer gtkmm24.
Please let me know if you don't want to update the packages yourself. I could request comaintainership in pkgdb and assist with the rebuilds or ask some provenpackager to do it.
Haïkel Guémar built new gtkmm24 in rawhide, closing the ticket.