Lenovo W520: display for one screen stretched over both when docked

When using the proprietary Nvidia drivers 331.113 or 346.35 the output from one window is often stretched to cover both by Unity. The standard xrandr-based Displays panel in System Settings shows both outputs, but nvidia-settings shows only the external monitor. 304.125 doesn't detect the monitor.

WORKAROUND: Use another window manager.

WORKAROUND: In Unity, manually configure the display output locations and sizes in ccsm.

WORKAROUND: Use nouveau.

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: xorg 1:7.7+7ubuntu2
ProcVersionSignature: Ubuntu 3.16.0-30.40-generic 3.16.7-ckt3
Uname: Linux 3.16.0-30-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 331.113 Mon Dec 1 21:08:13 PST 2014
 GCC version: gcc version 4.9.1 (Ubuntu 4.9.1-16ubuntu6)
.tmp.unity.support.test.0:

ApportVersion: 2.14.7-0ubuntu8.1
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: Tue Feb 3 11:00:10 2015
DistUpgraded: 2015-02-02 14:33:00,623 DEBUG enabling apt cron job
DistroCodename: utopic
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, including running git bisection searches
GraphicsCard:
 Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0126] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Device [17aa:21d1]
 NVIDIA Corporation GF108GLM [Quadro 1000M] [10de:0dfa] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Device [17aa:21d1]
InstallationDate: Installed on 2013-01-29 (735 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
MachineType: LENOVO 42763JU
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-30-generic root=UUID=9109c691-e957-4565-9b36-125458c0d242 ro quiet splash resume=UUID=9109c691e95745659b36125458c0d242:0x194ac758 crashkernel=384M-:128M
SourcePackage: xorg
UpgradeStatus: Upgraded to utopic on 2015-02-02 (0 days ago)
dmi.bios.date: 07/26/2013
dmi.bios.vendor: LENOVO
dmi.bios.version: 8BET62WW (1.42 )
dmi.board.asset.tag: Not Available
dmi.board.name: 42763JU
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:bvr8BET62WW(1.42):bd07/26/2013:svnLENOVO:pn42763JU:pvrThinkPadW520:rvnLENOVO:rn42763JU:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 42763JU
dmi.product.version: ThinkPad W520
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.12+14.10.20140918-0ubuntu1
version.ia32-libs: ia32-libs 20090808ubuntu36
version.libdrm2: libdrm2 2.4.56-1
version.libgl1-mesa-dri: libgl1-mesa-dri 10.3.2-0ubuntu0.1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.3.2-0ubuntu0.1
version.nvidia-graphics-drivers: nvidia-graphics-drivers N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.16.0-1ubuntu1.2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.0-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.4.0-2ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.914-1~exp1ubuntu4.1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu2
xserver.bootTime: Mon Feb 2 18:16:27 2015
xserver.configfile: /etc/X11/xorg.conf
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 16562
 vendor LEN
xserver.version: 2:1.16.0-1ubuntu1.2