Apr 24, 2019, 1:30 PM

Thank you Dmitryi.

cat /etc/X11/default-display-manager
gives me :

/usr/sbin/gdm3

echo $XDG_SESSION_TYPE
gives me :
x11

loginctl show-session 2 -p Type

gives me :

Type=x11

So I think x11 is turned on and not Wayland, so it seems OK.

I then installed lightdm and replaced gdm3 by lightdm as a display manager, thus :

cat /etc/X11/default-display-manager

gives me now :

/usr/sbin/lightdm

I tried launching SAMSON but nothing changed, maybe I have to reboot and re-try..
Thanks,
Robert