Windows slightly moved when using workspace switcher

[Manuel Schmid]

When using the workspace switcher, selecting a workspace can slightly move the window below the cursor. This can be quite annoying when using multiple workspaces with two semi-maximized windows each. Switching between the workspaces often moves the window a little bit so it appears in the task switcher of the neighboring workspaces.

Steps to reproduce:
- open two windows on one workspace
- semi-maximize them (i.e. ctrl+super+left/right)
- activate workspace switcher
- select the workspace while slightly moving the mouse
- the window below the cursor has now been slightly moved and appears in the task switcher of neighboring workspaces

I realize that this is more of a papercut bug report, but I find it quite noticeable and annoying with my workflow. It might also be less of a problem with other mice, but the touchpad of recent Thinkpads (e.g. X240) often moves the mouse slightly when the touchpad is pressed.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: compiz 1:0.9.12.1+15.04.20150410.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.19.0-22.22-generic 3.19.8-ckt1
Uname: Linux 3.19.0-22-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Mon Jul 13 18:57:50 2015
DistUpgraded: 2015-04-23 15:05:22,518 DEBUG enabling apt cron job
DistroCodename: vivid
DistroVariant: ubuntu
GraphicsCard:
 Intel Corporation Haswell-ULT Integrated Graphics Controller [8086:0a16] (rev 0b) (prog-if 00 [VGA controller])
   Subsystem: Lenovo ThinkPad X240 [17aa:2214]
InstallationDate: Installed on 2014-03-11 (489 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140310)
Lsusb:
 Bus 003 Device 002: ID 8087:8000 Intel Corp.
 Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 003: ID 04f2:b39a Chicony Electronics Co., Ltd
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: LENOVO 20AMA17X00
PackageArchitecture: all
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.19.0-22-generic root=/dev/mapper/system-root ro quiet splash vt.handoff=7
SourcePackage: compiz
UpgradeStatus: Upgraded to vivid on 2015-04-23 (81 days ago)
dmi.bios.date: 01/08/2014
dmi.bios.vendor: LENOVO
dmi.bios.version: GIET67WW (2.17 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20AMA17X00
dmi.board.vendor: LENOVO
dmi.board.version: Not Defined
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvrGIET67WW(2.17):bd01/08/2014:svnLENOVO:pn20AMA17X00:pvrThinkPadX240:rvnLENOVO:rn20AMA17X00:rvrNotDefined:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 20AMA17X00
dmi.product.version: ThinkPad X240
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.12.1+15.04.20150410.1-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.60-2
version.libgl1-mesa-dri: libgl1-mesa-dri 10.5.2-0ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.5.2-0ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.17.1-0ubuntu3
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.0-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.5.0-1ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917-1~exp1ubuntu2.2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu2build1
xserver.bootTime: Thu Jul 9 15:14:01 2015
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 1079
 vendor LGD
xserver.version: 2:1.17.1-0ubuntu3