How can I enable screenlock without turning off the monitor? (Ubuntu Gnome 14.04)

Solution 1:

This is not possible anymore in Gnome 3. You would have to execute gsettings set org.gnome.settings-daemon.plugins.power idle-dim-time [seconds] (possibly as lightdm as this is the user who runs the lockscreen) however this key doesn't exist anymore.

A possible workaround Khurshid mentioned is to install XScreenSaver (and set the timeout from there):

How can I change or install screensavers?

Solution 2:

This extension, "unblank", appears to work, I have only had it working for a minute now but my test shows that it keeps the display from turning off after pressing super + L.

https://extensions.gnome.org/extension/1414/unblank/