Julian, thanks for the detailed comment.
I assume that the only way to somewhat work around this problem is to change the recommendation orders:
lightdm: recommend lightdm-gtk-greeter | unity-greeter | ... xfce4-session: recommend light-locker | xscreensaver
This may cause trouble and unexpected behavior for non Xubuntu users though.
Julian, thanks for the detailed comment.
I assume that the only way to somewhat work around this problem is to change the recommendation orders:
lightdm: recommend lightdm-gtk-greeter | unity-greeter | ...
xfce4-session: recommend light-locker | xscreensaver
This may cause trouble and unexpected behavior for non Xubuntu users though.