Severe Qt visual corruption with default Qt theme under Unity

[Damon Lynch]

No doubt 'unity' is the wrong package, but I don't know the correct package name for the default theme when running Qt applications under Unity. Apologies for that.

Problem: when running many Qt applications in the Unity desktop, they are unusable because of severe visual corruption. The corruption is caused by the default Qt theme. On the command line, the error output is like this:

(vlc:8190): Gtk-CRITICAL **: IA__gtk_widget_style_get: assertion 'GTK_IS_WIDGET (widget)' failed

I have attached a screenshot showing the About window for VLC. The contents of the window are corrupted, and the window's title bar extend across the desktop.

When a Qt application allows the use of another theme, choosing a theme like "motif" eliminates the problem. This is why I'm fairly certain the bug is triggered by using the default Qt theme, and not Qt itself, or Qt applications. Moreover, on IRC another user could not replicate the problem when running under KDE.

The problem does not exist in Wily. Thank you.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: unity 7.4.0+16.04.20160209.3-0ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-4.19-generic 4.4.1
Uname: Linux 4.4.0-4-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 352.63 Sat Nov 7 21:25:42 PST 2015
 GCC version: gcc version 5.3.1 20160205 (Ubuntu 5.3.1-8ubuntu2)
ApportVersion: 2.19.4-0ubuntu2
Architecture: amd64
BootLog: /dev/sda5: clean, 226563/928416 files, 1770067/3713536 blocks
CurrentDesktop: Unity
Date: Sun Feb 14 18:27:27 2016
DistUpgraded: Fresh install
DistroCodename: xenial
DistroVariant: ubuntu
DkmsStatus:
 bbswitch, 0.8, 4.4.0-4-generic, x86_64: installed
 nvidia-352-updates, 352.63, 4.4.0-4-generic, x86_64: installed
 virtualbox, 5.0.14, 4.4.0-4-generic, x86_64: installed
GraphicsCard:
 NVIDIA Corporation GF108GLM [Quadro 1000M] [10de:0dfa] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Lenovo GF108GLM [Quadro 1000M] [17aa:21cf]
InstallationDate: Installed on 2016-02-13 (0 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Alpha amd64 (20160213)
MachineType: LENOVO 427637U
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-4-generic root=UUID=ba12a007-c38c-4532-921b-27f6fb9d0f03 ro noprompt persistent quiet splash
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)
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: 427637U
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:pn427637U:pvrThinkPadW520:rvnLENOVO:rn427637U:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 427637U
dmi.product.version: ThinkPad W520
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.12.2+16.04.20160209-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.66-2
version.libgl1-mesa-dri: libgl1-mesa-dri 11.1.1-1ubuntu2
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 11.1.1-1ubuntu2
version.nvidia-graphics-drivers: nvidia-graphics-drivers-* N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.17.3-2ubuntu2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.2-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.6.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20160127-1ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-1
xserver.bootTime: Sun Feb 14 17:56:06 2016
xserver.configfile: default
xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:

xserver.version: 2:1.17.3-2ubuntu2