>> Yes. This is because we are using org.gnome.Shell for End Session Dialog.
>> Other applications are thinking that we are GNOME Shell. I will try to make
>> patches for gnome-session and gnome-shell so we don't need to use
>> org.gnome.Shell for End Session Dialog.
It appears that GNOME developers are not really interested in
supporting sessions without GNOME Shell, but we can make a workaround:
$ gsettings set org.gnome.settings-daemon.plugins.xsettings overrides
"{'Gtk/ShellShowsAppMenu': <0>}"
It disables the Application menu, so fallback menus become visible.
It's possible set this setting on login, even set xsettings directly
from the gnome-flashback binary without touching the settings of
gnome-settings-daemon.