Show desktop is resulting in hidden app instance in expose

1. have multiple instance of an application
2. alt-tab in unity to "show desktop"
3. click on the unity launcher on the app to raise one instance
4. click again on the same launcher to trigger the expose mode

What happens:
-> the expose is behaving as if all app instances were visible, but only the instance which was previously raised is painted. See attached screenshot.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: compiz 1:0.9.8.4+bzr3412-0ubuntu1
ProcVersionSignature: Ubuntu 3.7.0-0.5-generic 3.7.0-rc4
Uname: Linux 3.7.0-0-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.6.2-0ubuntu3
Architecture: amd64
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,unitymtgrabhandles,workarounds,scale,expo,ezoom,unityshell]
CompositorRunning: compiz
Date: Fri Nov 16 19:13:27 2012
DistUpgraded: Fresh install
DistroCodename: raring
DistroVariant: ubuntu
EcryptfsInUse: Yes
GraphicsCard:
 Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0126] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Device [17aa:21da]
InstallationDate: Installed on 2012-05-28 (172 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
MachineType: LENOVO 4287CTO
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.7.0-0-generic root=UUID=a9f4b475-e4ce-45ed-aa33-9b92e52c49b0 ro quiet splash vt.handoff=7
SourcePackage: compiz
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/14/2012
dmi.bios.vendor: LENOVO
dmi.bios.version: 8DET58WW (1.28 )
dmi.board.asset.tag: Not Available
dmi.board.name: 4287CTO
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr8DET58WW(1.28):bd02/14/2012:svnLENOVO:pn4287CTO:pvrThinkPadX220:rvnLENOVO:rn4287CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 4287CTO
dmi.product.version: ThinkPad X220
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.8.4+bzr3412-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.39-0ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 9.0-0ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 9.0-0ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.13.0-0ubuntu6
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.3-0ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.0.0-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.20.9-0ubuntu2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.4-0ubuntu1
xserver.bootTime: Fri Nov 16 06:55:39 2012
xserver.configfile: default
xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.13.0-0ubuntu6
xserver.video_driver: intel