compiz leaks window handles (and pixmaps?)

Compiz leaks window handles when closing windows, according to xrestop.

To reproduce:
1) install xrestop ("apt-get install xrestop")
2) In a terminal, launch xrestop. Keep it running, and observe the number of 'Wins' and amount of pixmap memory ('Pxm mem') associated with the Compiz process
3) Open a new terminal (or any other) window. Observe that the number of windows had gone up by some amount. Opening a terminal window reliably results in exactly 3 extra window handles for the Compiz on my system.
4) Close the window

Expected results:
After closing the terminal window, the number of window handles held by the compiz process returns to the level observed in step 2

Actual results:
The number of window handles does not decrease; Compiz retains the window handles for the closed window. It's reliably 3 window handles for each terminal window on my system. I haven't checked other window types (dialogs, etc).

The above steps also produce a 1KB leak of pixmap memory on my system. I am not sure if this is related.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: compiz 1:0.9.8.4-0ubuntu2
ProcVersionSignature: Ubuntu 3.5.0-17.28-generic 3.5.5
Uname: Linux 3.5.0-17-generic x86_64
NonfreeKernelModules: nvidia
.proc.driver.nvidia.gpus.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 304.43 Sun Aug 19 20:14:03 PDT 2012
 GCC version: gcc version 4.7.2 (Ubuntu/Linaro 4.7.2-2ubuntu1)
.proc.driver.nvidia.warnings.fbdev:
 Your system is not currently configured to drive a VGA console
 on the primary VGA device. The NVIDIA Linux graphics driver
 requires the use of a text-mode VGA console. Use of other console
 drivers including, but not limited to, vesafb, may result in
 corruption and stability problems, and is not supported.
.tmp.unity.support.test.0:

ApportVersion: 2.6.1-0ubuntu3
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
Date: Thu Oct 11 15:04:36 2012
DistUpgraded: 2012-08-07 11:19:37,876 DEBUG enabling apt cron job
DistroCodename: quantal
DistroVariant: ubuntu
DkmsStatus:
 nvidia-current, 304.43, 3.5.0-17-generic, x86_64: installed
 virtualbox, 4.1.18, 3.5.0-14-generic, x86_64: installed
 virtualbox, 4.1.18, 3.5.0-15-generic, x86_64: installed
 virtualbox, 4.1.18, 3.5.0-16-generic, x86_64: installed
 virtualbox, 4.1.18, 3.5.0-17-generic, x86_64: installed
GraphicsCard:
 NVIDIA Corporation G84 [GeForce 8600M GT] [10de:0407] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Apple Inc. Device [106b:00a0]
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Beta amd64 (20100901.1)
JockeyStatus:
 kmod:nvidia_experimental_304 - Experimental NVIDIA binary Xorg driver, kernel module and VDPAU library (Proprietary, Disabled, Not in use)
 kmod:nvidia_173 - NVIDIA binary Xorg driver, kernel module and VDPAU library (Proprietary, Disabled, Not in use)
 kmod:nvidia_current_updates - NVIDIA binary Xorg driver, kernel module and VDPAU library (Proprietary, Disabled, Not in use)
 kmod:nvidia_173_updates - NVIDIA binary Xorg driver, kernel module and VDPAU library (Proprietary, Disabled, Not in use)
 kmod:nvidia_current - nvidia_current (Proprietary, Enabled, Not in use)
MachineType: Apple Inc. MacBookPro3,1
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.5.0-17-generic root=UUID=4b3d81ed-fb5d-4946-97c0-ec537e1bfa3f ro quiet splash
SourcePackage: compiz
UpgradeStatus: Upgraded to quantal on 2012-08-07 (65 days ago)
dmi.bios.date: 03/05/08
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MBP31.88Z.0070.B07.0803051658
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Mac-F4238BC8
dmi.board.vendor: Apple Inc.
dmi.board.version: PVT
dmi.chassis.asset.tag: Asset Tag#
dmi.chassis.type: 2
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-F4238BC8
dmi.modalias: dmi:bvnAppleInc.:bvrMBP31.88Z.0070.B07.0803051658:bd03/05/08:svnAppleInc.:pnMacBookPro3,1:pvr1.0:rvnAppleInc.:rnMac-F4238BC8:rvrPVT:cvnAppleInc.:ct2:cvrMac-F4238BC8:
dmi.product.name: MacBookPro3,1
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
version.compiz: compiz 1:0.9.8.4-0ubuntu2
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.nvidia-graphics-drivers: nvidia-graphics-drivers N/A
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 1:6.99.99~git20120913.8637f772-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.20.9-0ubuntu2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.2-0ubuntu3