By default, the screensaver timeout in Linux Mint is of 10 minutes and with the option of locking out the system enabled. What this means is that after 10 minutes of inactivity, the system will show a blank screen as screensaver and on pressing any key or detecting mouse activity it would need the user to re-enter the credentials to get back to desktop.
This can be annoying but can be changed as per one’s choice. To do this :
1. Go to Menu > Preferences > Screensaver.
2. Increase the slider so that screensaver timeout increases (maximum is 2 hours). Also, uncheck the option ” Lock screen when screensaver is active”. To disable the screensaver completely, uncheck the option ” Activate screensaver when computer is idle.” The type of screensaver can be changed too if desired.
3. Finally click “Close”.