Switching from internal QHD to external FullHD screen causes desktop redraw issues

[Harm van Bakel]

I have configured my display setup to automatically disable the internal laptop display when an external monitor is connected via the displayport.

In this configuration, when connecting a Dell developer laptop (XPS 9343) with a QHD (3200x1800) resolution to an external FHD (1920x1200) screen, the resolution and scaling updates correctly, but the desktop background stops redrawing properly. Apart from the top-left corner, the desktop area is not updated and any window moved over it will leave ghost images behind (see attached screenshot). It appears as if the physical size of the internal laptop display is somehow being used for the external monitor, and any region of the desktop outside this area is not refreshed.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: unity 7.2.5+14.04.20150603-0ubuntu1
ProcVersionSignature: Ubuntu 3.19.0-31.36~14.04.1-generic 3.19.8-ckt7
Uname: Linux 3.19.0-31-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.14.1-0ubuntu3.16
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: Sat Oct 17 15:42:53 2015
DistUpgraded: Fresh install
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-somerville-trusty-amd64-20140620-0
DistroCodename: trusty
DistroVariant: ubuntu
DkmsStatus:
 vboxhost, 5.0.6, 3.19.0-30-generic, x86_64: installed
 vboxhost, 5.0.6, 3.19.0-31-generic, x86_64: installed
EcryptfsInUse: Yes
GraphicsCard:
 Intel Corporation Broadwell-U Integrated Graphics [8086:1616] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Dell Device [1028:0665]
InstallationDate: Installed on 2015-08-06 (72 days ago)
InstallationMedia: Ubuntu 14.04 "Trusty" - Build amd64 LIVE Binary 20140620-04:25
MachineType: Dell Inc. XPS 13 9343
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-31-generic root=UUID=a25c6bbb-2787-44a4-a7f3-e90492f995db ro quiet splash pcie_aspm=force radeon.modeset=0 nouveau.modeset=0 "acpi_osi=Windows 2013" vt.handoff=7
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/14/2015
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A05
dmi.board.name: 0310JH
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA05:bd07/14/2015:svnDellInc.:pnXPS139343:pvr:rvnDellInc.:rn0310JH:rvrA00:cvnDellInc.:ct9:cvr:
dmi.product.name: XPS 13 9343
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.11.3+14.04.20150313-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.60-2~ubuntu14.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri N/A
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.xserver-xorg-core: xserver-xorg-core N/A
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel N/A
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A
xserver.bootTime: Sat Oct 17 09:54:36 2015
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 61463
 vendor DEL
xserver.version: 2:1.17.1-0ubuntu3.1~trusty1