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.
Post #10 here https://bbs.archlinux.org/viewtopic.php?id=171226 fixed it for me. I think I finally found a way to disable the inactivity curtain in gnome 3.10. Launch dconf-editor then drill down org > gnome > desktop> session. Find the key for idle-delay and change it's value to 0 .
Or you can do it in once step by running the command:
gsettings set org.gnome.desktop.session idle-delay 0
You'd think it would be easy to get rid of that annoying stuff...
Same problem in 18.04. So, I tested a bit. Despite disabling all settings of screensaver and lock screen, the lock screen was still active. But there is a solution. Turns out, the "gnome-screensaver" is still active in the background. Removing it (apt-get remove gnome-screensaver) does the trick. Now you can even enable the screensaver again and it won't lock the screen anymore ;)
In 17.10, I finally found that the entering Settings (top-right corner, then click the wrench in the drop-down), then changing Power -> Dim screen when inactive to OFF as well as Blank screen to Never worked.
I can't imagine what kind of thought process went into hiding these settings so far away in unintuitive locations would be a good idea, but that's what we're stuck with as a terrible default.
In my 17.04, there seems to be two places that involve lock:
Settings - Privacy
Settings - Brightness & Lock
That what you have in 17.10? If so, check that Brightness & Lock show Lock being OFF.
Get rid of the annoying "pull me up I don't make any sense" screen shield in GNOME 3
https://extensions.gnome.org/extension/672/disable-screen-shield/