Background sessions only show black screen

[Rüdiger Kupper]

If multiple users are logged into desktop sessions, only the session in the foreground is correctly exported. Connecting to a background session works, but only shows a black screen.
This is independent from the VNC client (tried vinagre and remmina).

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: vino 3.4.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-24.37-generic 3.2.14
Uname: Linux 3.2.0-24-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.0.1-0ubuntu7
Architecture: amd64
Date: Tue May 8 14:06:39 2012
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
SourcePackage: vino
UpgradeStatus: Upgraded to precise on 2012-04-28 (10 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Alexandre Magno (alexandre-mbm)]

What is a background session? I think it's something for that I look...