Do you use the same group name for the widget and the window?
If yes, there may be some preemption of the accel by the widget…
I’m not sure how exactly that works though, I personally always use different group names…
All actions and group names in my app are generated with uuid_string_random because I’m working with objects only and won’t to care about namespace conflicts
Accels work only when I attach its group to the ApplicationWindow (e.g. impl GtkWindow). Maybe that’s no problem, but interesting, even I have lot of other questions intuitively not understandable for me as for beginner in GTK ecosystem