Fix screen locking failures

Registered by Kees Cook

There is an ever-growing number of bugs around the general category of "failure to lock screen". The root causes are likely numerous, and should be identified and squashed:
 - https://bugs.launchpad.net/bugs/317995 (Gnome)
 - https://bugs.launchpad.net/bugs/344803 (Gnome)
 - https://bugs.launchpad.net/bugs/338057 (Gnome)
 - https://bugs.launchpad.net/bugs/345026 (Gnome)
 - https://bugs.launchpad.net/bugs/353460 (Gnome)
 - https://bugs.launchpad.net/bugs/355027 (Gnome)
 - https://bugs.launchpad.net/bugs/283315 (KDE)
 - https://bugs.launchpad.net/bugs/291712 (KDE)
 - https://bugs.launchpad.net/bugs/296085 (KDE)
 - https://bugs.launchpad.net/bugs/326721 (KDE)
 - https://bugs.launchpad.net/bugs/349427 (XFCE)
 - https://bugs.launchpad.net/bugs/316907 (LXDE)

Blueprint information

Status:
Not started
Approver:
Rick Clark
Priority:
Undefined
Drafter:
Kees Cook
Direction:
Needs approval
Assignee:
None
Definition:
Discussion
Series goal:
None
Implementation:
Unknown
Milestone target:
None

Related branches

Sprints

Whiteboard

I. Current status
  A. Gnome, KDE, Xfce screen saver bug review
II. Specific root-causes
  B. Menu-focus blocks screenlocking
  C. gnome-power-manager does not always do the right thing
III. Future tracking, documentation, fixes, etc

(?)

Work Items

This blueprint contains Public information 
Everyone can see this information.