Not starting without XDG_CURRENT_DESKTOP=GNOME
gnome-control-center does not start without setting XDG_CURRENT_DESKTOP=GNOME. However it's being used on other desktop environments and WMs as well, like evolution is used on Xfce or whatever and therefore gnome-online-accounts and gnome-control-center could be useful as well. gnome-online-accounts cannot be used without the gnome-control-center.