[Regression] Computer should NOT shutdown from Guest or Standard user while an Administrator user is still logged in

Computer should not shutdown/restart from a Guest session or from a Standard user session while there is still an Administrator user logged in. This is a major regression from Ubuntu 12.04. This poses a huge data loss potential.

The easy way to solve this is to follow 12.04's policy. The computer can not shutdown/restart from any session while there are any other session logged in regardless it is Administrator, Standard or Guest session.

The hard way is to follow this proposed policy:

(A) Guest session can not shutdown/restart while there are any sessions logged in regardless they are Standard or Administrator users.

(B) Standard user can not shutdown/restart while there is an Administrator user or another Standard user logged in.

(C) Standard user can shutdown/restart while there is a Guest session logged in.

(D) Administrator user can shutdown/restart while there is a Standard or Guest session logged in.

(E) Administrator user can not shutdown/restart while there is still another Administrator user logged in.

1- In case of (A), a Guest tries to shutdown/restart, a message should pop up telling the Guest that s/he can not shutdown/restart but the session can be logged off, and maybe give a reason for that.

2- In case of (B), a Standard user tries to shutdown/restart, a message should pop up telling the Standard user that s/he can not shutdown/restart but the session can be logged off, and maybe give a reason for that.

3- In case of (C), a Standard user tries to shutdown/restart, a message should pop up telling the Standard user that s/he can shutdown/restart but the Guest could lose their data if not saved on external storage such as a USB stick, and advice him/her to log off that session first then shutdown/restart.

4- In case of (D), an Administrator user tries to shutdown/restart, a message should pop up telling the Administrator user that s/he can shutdown/restart but other users could lose their data if not saved, and advice him/her to log off those sessions first then shutdown/restart.

5- In case of (E), an Administrator user tries to shutdown/restart, a message should pop up telling the Administrator user that s/he can not shutdown/restart but the session can be logged off, and maybe give a reason for that.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: lightdm 1.9.13-0ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-20.42-generic 3.13.7
Uname: Linux 3.13.0-20-generic x86_64
ApportVersion: 2.13.3-0ubuntu1
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Apr 1 10:33:39 2014
InstallationDate: Installed on 2014-03-08 (23 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140304)
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)