I have a glade-based UI for gtk3, and I set accelerators fields for several menuitems. I'm not sure what GtkBuilder does exactly behind the scenes when it's loading the glade file (use a global GtkAccelGroup?), but the end result is, when I hide the menubar, the accelerator shortcuts stop working.
I'm wondering whether there is a way of getting the accelerators working even when the menu is not visible, while still sticking to glade as much as possible.
Maybe you can try to stick the accelerators not to the menu, but one level higher in your application, for example the window? In my own application I do it like this.
The two menu assignments have their own accelerators which are working even when not visible.
Does this help you?