Setting screen locker type to "Simple locker" displays a screen that says: "The session has been locked by $user". However, if the "Require password" option is un-ticked, the message will just disappear at a wave of the mouse. This is arguably a security hazard (user thinks session is locked). Proposed solution: setting Screen Locker Type to "Simple Locker" should disable (grey-out) the "Require password after __" setting, and should ALWAYS require the password (because the screen says session is locked). Reproducible: Always Brace yourselves for massive duplication of this bug in about a week's time; this is set to be the default setting in the forthcoming openSUSE 12.3 release.
Better to fix bug #315442 which I'm finally working on, sorry about this,