Hello!
We use core24 and [gnome] extension for build our snap. We found libgtkmm-4.0 inside [gnome] extension:
/snap/gnome-46-2404/168$ find | grep libgtkmm
./usr/lib/x86_64-linux-gnu/libgtkmm-4.0.so
./usr/lib/x86_64-linux-gnu/libgtkmm-4.0.so.0
./usr/lib/x86_64-linux-gnu/libgtkmm-4.0.so.0.0.0
but there is not libgtkmm-3.0. We also found libgtk-3:
/snap/gnome-46-2404/168$ find | grep libgtk-3.so
./usr/lib/x86_64-linux-gnu/libgtk-3.so
./usr/lib/x86_64-linux-gnu/libgtk-3.so.0
./usr/lib/x86_64-linux-gnu/libgtk-3.so.0.2418.32
Our app uses GTKMM-3.0. Could you please add libgtkmm-3.0 to [gnome] extension? We will be grateful to you for this.
Thank you!