Font corruption some characters suddenly not rendered after login or after a period of usage

[Robert Tuck]

This has occurred multiple times on my machine (Dell Inspiron 13 7000 series laptop), it happens without warning. After which time suddenly application windows will fail to render certain characters making everything unreadable. In the past it has happened immediately after login, this time it happened after ~30 minutes usage from a cold boot.

See attached screenshot.
This doesn't happen for every window, chrome is generally ok, as are the unity launcher. The tools in the system tray and the power off menu are affected, as are nautilus, gedit, and application menus generally.
Rolling over labels sometimes causes them to rener properly while the mouse is over them.

Terminal is fine

There is a workaround which is to change the font antialiasing settings with unity tweak tool, however this isn't a permanent fix - last time it was set to RGBA, so I changed it to Grayscale. This time it happened it was set to Grayscale and I set it to RGBA and it fixes it.

I don't know enough to know whether this is a video driver issue, or a problem with gtk or what, so it's possible you may need to recategorise this defect.

One other thing that may be useful info is that twiddling the antialiasing drop-down fixes and breaks the font rendering on the fly, when I see this problem.

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: xorg 1:7.7+7ubuntu2
ProcVersionSignature: Ubuntu 3.16.0-34.45-generic 3.16.7-ckt8
Uname: Linux 3.16.0-34-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.14.7-0ubuntu8.4
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 Apr 20 06:39:41 2015
DistUpgraded: Fresh install
DistroCodename: utopic
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Intel Corporation Broadwell-U Integrated Graphics [8086:1616] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Dell Device [1028:0675]
InstallationDate: Installed on 2015-04-05 (14 days ago)
InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
MachineType: Dell Inc. Inspiron 7348
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-34-generic.efi.signed root=/dev/mapper/LVM_VG1-root ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/26/2014
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A01
dmi.board.name: 08FH29
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: A01
dmi.modalias: dmi:bvnDellInc.:bvrA01:bd11/26/2014:svnDellInc.:pnInspiron7348:pvrA01:rvnDellInc.:rn08FH29:rvrA00:cvnDellInc.:ct10:cvrA01:
dmi.product.name: Inspiron 7348
dmi.product.version: A01
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.12+14.10.20140918-0ubuntu1
version.ia32-libs: ia32-libs N/A
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.xserver-xorg-core: xserver-xorg-core 2:1.16.0-1ubuntu1.3
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~exp1ubuntu4.2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu2
xserver.bootTime: Mon Apr 20 05:54:03 2015
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 19528
 vendor SDC
xserver.version: 2:1.16.0-1ubuntu1.3

[penalvch (penalvch)]

Robert Tuck, thank you for reporting this and helping make Ubuntu better.

As per https://wiki.ubuntu.com/Releases, Ubuntu 14.10 went EOL on July 23, 2015.

Is this reproducible in a supported release?

[Eugene Romanenko (eros2)]

Same issue on Lenovo Flex 2-14, intel driver (nvidia card disabled) with Ubuntu 16.04.

[Eugene Romanenko (eros2)]

Issue sometines appear after resume or switching user.

[Robert Tuck (robt-majormajor)]

The laptop is now on 15.10 and I have not seen the bug. It may have been fixed in 15.04, I can't remember it was so long ago since I did that upgrade.

[penalvch (penalvch)]

Robert Tuck, this bug report is being closed due to your last comment https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1446053/comments/5 regarding this being fixed with an update. For future reference you can manage the status of your own bugs by clicking on the current status in the yellow line and then choosing a new status in the revealed drop down box. You can learn more about bug statuses at https://wiki.ubuntu.com/Bugs/Status. Thank you again for taking the time to report this bug and helping to make Ubuntu better. Please submit any future bugs you may find.