For https://gitlab.gnome.org/GNOME/Initiatives/issues/4, the application menu is being retired, with it's contents being moved into the in-window primary window. When removing a menu, the shortcuts for it's actions (if defined in the menu) are also removed. The "Quit" shortcut is now defined in src/gcal-window.c. Related to https://gitlab.gnome.org/GNOME/gnome-calendar/issues/319