In 17.10 I've looked in Settings->Privacy, Screen Lock is off. In Power Blank Screen is off. Yet after some minutes of inactivity the screen just doesn't turn off, a lock screen appears that needs the mouse to pull up.
This is a PC in my house, I'm really not concerned that one of the dogs could wander by and see my screen. Is there a way to really turn off this lock screen? Turning the display off after some minutes would be fine.