title: Ubuntu, lock screen but do not screensave
body: <p>When I do not use my graphical session anymore, the screensaver automatically lock it and power off the screen to save energy. </p>
  
  <p>I want it to keep locking my session but not to power off the screen, is it possible ? </p>
  
  <p>I use Ubuntu 18.04 with default gnome display manager. </p>
  
  <p>Thank you,</p>
  
  <p>Matias </p>