How to lock screen laptop in Mini

We can implement keyboard shortcuts for dm-tool in the openbox config file:

~/.config/openbox/trisquel-mini-rc.xml

The forum would not show anything sporting xml tags, so I attached them as a text file.

It appears that clicking on the "Lock screen" button in the logout menu does not work either, which is presumably what you were referring to. Using the keyboard shortcuts above should provide an acceptable workaround, else we will need to dive further into the lxsession config files to fix that unresponsive button.

UPDATE: the button is not working because no screen locker is installed by default. Installing the light-locker package fixes the problem. You need to run light-locker (Alt+F2) after installing it, or to log out and back in. Light-locker comes with a neat configuration tool, available in "Preferences" in the main menu.