Disconnecting and reconnecting external monitor results in display corruption at screen edges

[Harm van Bakel]

Disconnecting and reconnecting an external monitor in Unity results in the outermost pixel rows and columns at the screen edges to assume the color of any window that is dragged over them. Those colors then persist, resulting in permanent border artifacts. This issue is only resolved after restarting or logging out and logging in again.

Steps to reproduce:
1. Connect an external monitor to a laptop and set up the display configuration to disable the internal display when the external monitor is connected.
2. Now, with the external monitor enabled and the laptop display disabled, disconnect the external monitor by unplugging the display cable. The internal laptop display will activate.
3. Reconnect the external monitor and wait for the displays to revert to the external-monitor only configuration.
4. Open any window, drag it across the screen edge and away from the edge again. You should now observe that there is a set of pixels at the screen edge that retains the window color (white in the attached example pictures).

The correct behavior should be that the pixels at the edge should not retain a 'ghost image' of the window that was dragged over it.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: unity 7.4.0+16.04.20160715-0ubuntu1
Uname: Linux 4.9.4-040904-generic x86_64
.tmp.unity_support_test.0:

ApportVersion: 2.20.1-0ubuntu2.4
Architecture: amd64
BootLog:

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 Jan 16 09:48:53 2017
DistUpgraded: Fresh install
DistroCodename: xenial
DistroVariant: ubuntu
EcryptfsInUse: Yes
GraphicsCard:
 Intel Corporation Sky Lake Integrated Graphics [8086:1926] (rev 0a) (prog-if 00 [VGA controller])
   Subsystem: Dell Skylake Integrated Graphics [1028:0704]
InstallationDate: Installed on 2016-09-09 (129 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 004: ID 046d:c52f Logitech, Inc. Unifying Receiver
 Bus 001 Device 003: ID 046d:c318 Logitech, Inc. Illuminated Keyboard
 Bus 001 Device 002: ID 0451:8142 Texas Instruments, Inc. TUSB8041 4-Port Hub
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Dell Inc. XPS 13 9350
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.9.4-040904-generic root=UUID=9ea8050f-e2c0-45a1-97b4-b8991d475c6e ro i915.enable_guc_loading=2 i915.enable_guc_submission=2 quiet splash vt.handoff=7
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/30/2016
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.4.12
dmi.board.name: 0H67KH
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.4.12:bd11/30/2016:svnDellInc.:pnXPS139350:pvr:rvnDellInc.:rn0H67KH:rvrA00:cvnDellInc.:ct9:cvr:
dmi.product.name: XPS 13 9350
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.12.2+16.04.20160823-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.67-1ubuntu0.16.04.2
version.libgl1-mesa-dri: libgl1-mesa-dri 1:13.0.3-3~x~padoka0
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 1:13.0.3-3~x~padoka0
version.xserver-xorg-core: xserver-xorg-core 2:1.18.4-0ubuntu0.2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.10.1-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.7.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20160325-1ubuntu1.2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-1build2