Sometimes the graphics starts acting strange and I need to restart sddm. But when I do, a new user session is created and I lose what I was doing before. How can I restart sddm and log to the active session before restarting?
SnapOverflow
This is probably not possible.
AFAIK, on login a special process is started which leads the session. All child processes of this session leader process belong to the same session. If the session leader process becomes terminated all child processes are terminated as well. Processes cannot be reassigned to other sessions.
Restarting SDDM probably kills the session leader process and thus all processes of the session.