Devuan GNU+Linux is a free software operating system for your
computer. Free software means you are free to use, copy
and distribute, study, change the software, and share your
modifications with the community.
software freedom, your way
apt install xfce4-session
xfce : optional
Xfce4 Session Manager
xfce4-session is an X11-compliant "session manager" designed for use with
the Xfce4 Desktop Environment. On log out, the session manager saves the
state of all your running applications. When you log back in, the session
manager restores the same applications with the same window positions.