Lock screen doesn't work

In my installation of Trisquel mini the lock screen function doesn't work even if you let the pc unused for several hours, I have solved the problem installing the xscreensaver package however I believe that this is a bug for an optimal out of the box experience (because I have set not to login automatically during the bootstrap, I presume that the distro should lock for privacy reason the screen after maybe ten minutes), how can I highlight that on the Bug tracking system?