Even more interesting... I'm developing a small game in SDL. It runs in a window, hides the cursor, and in every frame moves the cursor to the center of the window. But if I move the mouse fast enough for the cursor to exit the window, it is shown for a split second and, more importantly, that black rectangle flashes in the screen under the cursor.
So, this graphical glitch occurs when the mouse cursor is shown or hidden! This bug can be easily reproduced by following these steps: 1. Open a gnome-terminal 2. Move the mouse cursor to inside the window 3. Press and hold any letter in the keyboard, like 'A', to enter that letter repeatedly into the terminal, which will also hide the mouse cursor 4. Start moving the mouse cursor, keeping it inside the window, and the problem will manifest This issue occurs also in a guest session and a live session (after I disable the phantom 2nd monitor due to NVidia Optimus), so it's not because of any change I made to the system. And like I said above, I'm using a laptop with Nvidia Optimus (Nvidia driver installed, Intel card selected). I also just now tried reproducing this bug in GNOME Session Flashback, and I managed to reproduce it both with Compiz and Metacity. So, this issue isn't neither in Unity nor in Compiz! Maybe in X11. Could a developer take a look into this issue? I think there's enough info to go on now. If you need more info, just ask. ** Also affects: xorg-server (Ubuntu) Importance: Undecided Status: New ** Changed in: compiz (Ubuntu) Status: New => Invalid ** Changed in: unity (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1585329 Title: Sometimes a black rectangle appears briefly under the mouse cursor Status in compiz package in Ubuntu: Invalid Status in unity package in Ubuntu: Invalid Status in xorg-server package in Ubuntu: New Bug description: I'm on 16.04, using a laptop with Nvidia Optimus (Nvidia driver installed, Intel card selected). The problem also occurs in a guest session. It didn't occur in 14.04. Sometimes I see a black rectangle appear for a very brief moment (a flash). Horizontally, the rectangle occupies the whole screen. Vertically, the rectangle seems to start in the mouse cursor and ends in the bottom of the screen. The easiest way to reproduce the bug is to open a Gnome terminal, move the mouse cursor inside the window and press Alt+Backspace repeatedly. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: compiz 1:0.9.12.2+16.04.20160415-0ubuntu1 ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8 Uname: Linux 4.4.0-22-generic x86_64 .tmp.unity_support_test.0: ApportVersion: 2.20.1-0ubuntu2 Architecture: amd64 CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,staticswitcher,workarounds,scale,expo,ezoom,dbus] CompositorRunning: compiz CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0' CompositorUnredirectFSW: true CurrentDesktop: Unity Date: Tue May 24 19:44:19 2016 DistUpgraded: Fresh install DistroCodename: xenial DistroVariant: ubuntu EcryptfsInUse: Yes GraphicsCard: Intel Corporation Core Processor Integrated Graphics Controller [8086:0046] (rev 02) (prog-if 00 [VGA controller]) Subsystem: Acer Incorporated [ALI] Core Processor Integrated Graphics Controller [1025:0488] NVIDIA Corporation GF108M [GeForce GT 420M] [10de:0df1] (rev ff) (prog-if ff) GsettingsChanges: b'org.compiz.core' b'outputs' b"['1366x768+0+0']" b'org.compiz.core' b'hsize' b'2' b'org.compiz.core' b'active-plugins' b"['core', 'composite', 'opengl', 'compiztoolbox', 'imgpng', 'snap', 'titleinfo', 'grid', 'vpswitch', 'move', 'regex', 'copytex', 'place', 'mousepoll', 'session', 'commands', 'wall', 'resize', 'winrules', 'dbus', 'unitymtgrabhandles', 'animation', 'expo', 'ezoom', 'fade', 'workarounds', 'scale', 'unityshell']" b'org.compiz.core' b'vsize' b'2' b'org.compiz.core' b'focus-prevention-level' b'0' InstallationDate: Installed on 2016-04-25 (28 days ago) InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1) Lsusb: Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 003: ID 064e:a219 Suyin Corp. 1.3M WebCam (notebook emachines E730, Acer sub-brand) Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub MachineType: Acer Aspire 5742G PackageArchitecture: all ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.4.0-22-generic root=UUID=68a53fa4-4cfc-45bc-84de-762947ea37e1 ro locale=pt_PT quiet splash SourcePackage: compiz UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 08/13/2012 dmi.bios.vendor: Acer dmi.bios.version: V1.30 dmi.board.asset.tag: Base Board Asset Tag dmi.board.name: Aspire 5742G dmi.board.vendor: Acer dmi.board.version: V1.30 dmi.chassis.type: 10 dmi.chassis.vendor: Acer dmi.chassis.version: V1.30 dmi.modalias: dmi:bvnAcer:bvrV1.30:bd08/13/2012:svnAcer:pnAspire5742G:pvrV1.30:rvnAcer:rnAspire5742G:rvrV1.30:cvnAcer:ct10:cvrV1.30: dmi.product.name: Aspire 5742G dmi.product.version: V1.30 dmi.sys.vendor: Acer version.compiz: compiz 1:0.9.12.2+16.04.20160415-0ubuntu1 version.ia32-libs: ia32-libs N/A version.libdrm2: libdrm2 2.4.67-1 version.libgl1-mesa-dri: libgl1-mesa-dri 11.2.0-1ubuntu2 version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A version.libgl1-mesa-glx: libgl1-mesa-glx 11.2.0-1ubuntu2 version.xserver-xorg-core: xserver-xorg-core 2:1.18.3-1ubuntu2 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 version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-1build2 xserver.bootTime: Tue May 24 19:18:29 2016 xserver.configfile: default xserver.errors: xserver.logfile: /var/log/Xorg.0.log xserver.outputs: product id 592 vendor LGD xserver.version: 2:1.18.3-1ubuntu2 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/compiz/+bug/1585329/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp