The intention is to prevent someone local to the computer from just pulling the power cord or hitting the reset button when the system is locked and they want to shut it down or log in as a different user. I believe these dialog options are configurable via PolicyKit if you've taken the time to harden the local environment as for kiosk use or similar,
Thanks ** Information type changed from Private Security to Public Security ** Changed in: lightdm (Ubuntu) Status: New => Opinion -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lightdm in Ubuntu. https://bugs.launchpad.net/bugs/1434486 Title: System management options on lockscreen Status in lightdm package in Ubuntu: Opinion Bug description: When I'm lock the screen it's possible to turn off computer or restart it. This possibility on lock screen makes all lock screen idea no sense. When I'm lock the screen I want to no one was able to unlock it, turn off or reboot. ProblemType: Bug DistroRelease: Ubuntu 14.10 Package: lightdm 1.12.2-0ubuntu1 ProcVersionSignature: Ubuntu 3.16.0-26.35-generic 3.16.7-ckt1 Uname: Linux 3.16.0-26-generic x86_64 ApportVersion: 2.14.7-0ubuntu8.2 Architecture: amd64 CurrentDesktop: Unity Date: Fri Mar 20 10:47:07 2015 InstallationDate: Installed on 2014-04-19 (335 days ago) InstallationMedia: Ubuntu-Server 14.04 LTS "Trusty Tahr" - Release amd64 (20140416.2) SourcePackage: lightdm UpgradeStatus: Upgraded to utopic on 2014-11-06 (133 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lightdm/+bug/1434486/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp