Display Turns Black When Unity's Dash is opened (16.04 LTS)

[Gustav]

>> What's the problem?

When opening Unity's Dash in Ubuntu 16.04 (either by clicking on the uppermost icon of the launcher called “Search” or by a keyboard shortcut “Super + Tab”), the display of a connected external monitor (3440x1440, 21:9) turns completely black if, and only if there is another window (e.g. with Firefox, gedit, Nautilus) beneath the just opening dash. The monitor also goes into stand-by.

When closing the Dash (e.g. by pressing the Esc key – while the display is black) the monitor will display the desktop again.

The black screen bug also appears when activating Unity's “spreading all windows” function by clicking on such launcher icons which has more than one instance of an application opened (e.g. two terminals are opened) and if there remain other windows beneath (e.g. gedit window).

This problem does not occur with Ubuntu <= 15.10 !

-------------------------------------------------

>> How to reproduce the bug?

Use a Lenovo Thinkpad T450s with a ThinkPad Pro Dock. Leave the laptop lid closed and connect an external monitor (e.g. a Dell U3415W) via DisplayPort 1.2; use monitors native resolution which is 3440x1440 with 60 Hz. Start Ubuntu 16.04 (either from a LiveUSB/LiveCD stick or from a partition where Ubuntu is installed incl. all updates).

Open one or more windows, e.g. with Firefox, gedit, Nautilus, and place them in the upper left corner of the display where the Dash usually appears when opening it. Then open the Dash (with mouse click or shortcut). BANG -> the whole screen turns black. Press Esc to close the Dash and colours come back.

The bug also happens when using dual monitoring. In this case only the display with 3440x1440 turns black when opening the Dash. This bug doesn't appear when only using the notebooks build in display.

Again: This problem does not occur with Ubuntu <= 15.10 !

-------------------------------------------------

>> What work arounds did I figure out?

1) Pressing Esc key will close the Dash, which brings back the picture. But with this work around the Dash is still useless of course.

2) Minimize all windows (e.g. by pressing the launcher's icon “Show Desktop”). Then the Dash appears and the display doesn't turn black – because there are no windows underneath the Dash. Of course this could be a temporary workaround, but in the long run it would be very annoying to have minimized all windows before using the Dash.

3) When changing the monitors resolution to 2560x1080 the bug will not appear. This could be only a temporary workaround, because I'm not using a large-scale monitor to have a ancient resolution.

4) Using a complete different desktop than Unity, e.g. Cinnamon or Gnome, which is a pity, because I get used to Unity.

Once again:

- This problem (black screen) does not occur with Ubuntu <= 15.10 !

- The bug is not caused due to my personal configurations of Ubuntu, because the bug occurs with a Ubuntu 16.04 LiveUSB as well as with a installed Ubuntu incl. all updates.

- The bug seems not to appear with resolutions smaller than 3440x1440 (but I haven't tested where exactly the limits lie).

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: unity 7.4.0+16.04.20160906-0ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-64.85-generic 4.4.44
Uname: Linux 4.4.0-64-generic x86_64
.tmp.unity_support_test.0:

ApportVersion: 2.20.1-0ubuntu2.5
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: Fri Feb 24 08:48:19 2017
DistUpgraded: Fresh install
DistroCodename: xenial
DistroVariant: ubuntu
GraphicsCard:
 Intel Corporation Broadwell-U Integrated Graphics [8086:1616] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Broadwell-U Integrated Graphics [17aa:5036]
InstallationDate: Installed on 2016-09-23 (153 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
MachineType: LENOVO 20BX0011GE
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-64-generic.efi.signed root=UUID=e515c051-7a9a-44d4-bb0e-a63486526c63 ro noprompt quiet splash vt.handoff=7
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/21/2015
dmi.bios.vendor: LENOVO
dmi.bios.version: JBET49WW (1.14 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20BX0011GE
dmi.board.vendor: LENOVO
dmi.board.version: SDK0E50510 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrJBET49WW(1.14):bd05/21/2015:svnLENOVO:pn20BX0011GE:pvrThinkPadT450s:rvnLENOVO:rn20BX0011GE:rvrSDK0E50510WIN:cvnLENOVO:ct10:cvrNone:
dmi.product.name: 20BX0011GE
dmi.product.version: ThinkPad T450s
dmi.sys.vendor: LENOVO
upstart.unity7.log:
 WARN 2017-02-24 08:46:04 unity.iconloader IconLoader.cpp:756 Unable to load icon file:/// at size -1x22: Can't open directory
 ATTENTION: default value of option force_s3tc_enable overridden by environment.
 WARN 2017-02-24 08:48:01 unity.iconloader IconLoader.cpp:264 Unable to load icon qmlscene at size 64
version.compiz: compiz 1:0.9.12.2+16.04.20160823-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.70-1~ubuntu16.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 12.0.6-0ubuntu0.16.04.1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 12.0.6-0ubuntu0.16.04.1
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
xserver.bootTime: Fri Feb 24 08:44:08 2017
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 4925
 vendor AUO
xserver.version: 2:1.18.4-0ubuntu0.2

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Jendrik Seipp (jendrikseipp)]

I have the exact same problem. In addition, for me the display also turns black when I open or switch to Thunderbird. Have you found a way to fix the problem or which workaround do you use?

[Jendrik Seipp (jendrikseipp)]

Another data point: The issue persists with the newest HWE kernel (4.10) and also if "low graphics mode" is enabled in CCSM.

[Khurshid Alam (khurshid-alam)]

@Jendrik,

Is it reproducible on 17.10 or even 18.04?