In XFCE, it is possible that the window manager (XFWM) does not restart after an update.
This will result in an XFCE session starting with all the windows stuck at the upper-left corner.
This can be fixed by relaunching the XCFE window manager.
To be sure that this is started correctly when session is launched, add that to $HOME/.xinitrc.
exec sleep 5 && xfwm4 --replace