One more discovery. If I go to console terminal (e.g. "Ctrl-Alt-F3") first before turning off the screen, I can get my session back then by turning on the screen then back to GUI (i.e. "Ctrl-Alt-F1").
One more discovery. If I go to console terminal (e.g. "Ctrl-Alt-F3") first before turning off the screen, I can get my session back then by turning on the screen then back to GUI (i.e. "Ctrl-Alt-F1").