lxsession-logout does not properly shade the entire screen when logging out with two mirrored monitore of the same size.

To reproduce open lubuntu with multiple monitors of different sizes but have them show the same display. Then in the menu in LXDE select logout. Only the part that appears on both monitors will be shaded.

lxsession-logout:
  Installed: 0.5.2-0ubuntu2
  Candidate: 0.5.2-0ubuntu2
  Version table:
 *** 0.5.2-0ubuntu2 0
        500 http://us.archive.ubuntu.com/ubuntu/ wily/universe amd64 Packages
        100 /var/lib/dpkg/status

\Description: Ubuntu Wily Werewolf (development branch)
Release: 15.10
I expected the entire screen and bacoud area to be shaded instead only the area on both monitors was shaded.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: lxsession-logout 0.5.2-0ubuntu2
ProcVersionSignature: Ubuntu 4.1.0-3.3-generic 4.1.3
Uname: Linux 4.1.0-3-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.18-0ubuntu5
Architecture: amd64
CurrentDesktop: LXDE
Date: Mon Aug 3 17:12:01 2015
InstallationDate: Installed on 2015-06-02 (62 days ago)
InstallationMedia: Lubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20150602)
SourcePackage: lxsession
UpgradeStatus: No upgrade log present (probably fresh install)