The entire UI is constructed with templates, so the wrapper
constructors are never called, except for gtk_inspector_window_new,
which gets called from the GTK+ code.
Show the actions that are added to GtkApplication and
GtkApplicationWindows, as well as action groups that are
inserted elsewhere with gtk_widget_insert_action_group.
https://bugzilla.gnome.org/show_bug.cgi?id=730095
