After the upgrade to 5.9, the alt-tab effects (coverswitch and flipswitch) have rendering issues in a multiscreen setup. I have three screens. With only one screen attached all works fine. With two screens attached, flipswitch works fine. coverswitch is usable, but has rendering artifacts in the lower right corner (looks like upside down window content). With three screens both effects result in windows being stretched across screens, with the coverswitch effect again showing rendering artifacts. This happens on a Nvidia Quadro NVS-510 (NVE7) and nouveau. Mesa 13.0.4.
Please provide the output of: qdbus org.kde.KWin /KWin supportInformation
KWin Support Information: The following information should be used when requesting support on e.g. http://forum.kde.org. It provides information about the currently running instance, which options are used, what OpenGL driver and which effects are running. Please post the information provided underneath this introductory text to a paste bin service like http://paste.kde.org instead of pasting into support threads. ========================== Version ======= KWin version: 5.9.2 Qt Version: 5.7.1 Qt compile version: 5.7.1 XCB compile version: 1.12 Operation Mode: X11 only Build Options ============= KWIN_BUILD_DECORATIONS: yes KWIN_BUILD_TABBOX: yes KWIN_BUILD_ACTIVITIES: yes HAVE_INPUT: yes HAVE_DRM: yes HAVE_GBM: yes HAVE_X11_XCB: yes HAVE_EPOXY_GLX: yes HAVE_WAYLAND_EGL: no X11 === Vendor: The X.Org Foundation Vendor Release: 11901000 Protocol Version/Revision: 11/0 SHAPE: yes; Version: 0x11 RANDR: yes; Version: 0x14 DAMAGE: yes; Version: 0x11 Composite: yes; Version: 0x4 RENDER: yes; Version: 0xb XFIXES: yes; Version: 0x50 SYNC: yes; Version: 0x31 GLX: yes; Version: 0x0 Decoration ========== Plugin: org.kde.breeze Theme: Blur: 0 onAllDesktopsAvailable: true alphaChannelSupported: true closeOnDoubleClickOnMenu: false decorationButtonsLeft: 0, 2, 9 decorationButtonsRight: 6, 3, 4, 5 borderSize: 3 gridUnit: 10 font: DejaVu Sans,10,-1,5,50,0,0,0,0,0 smallSpacing: 2 largeSpacing: 10 Options ======= focusPolicy: 1 nextFocusPrefersMouse: true clickRaise: true autoRaise: false autoRaiseInterval: 750 delayFocusInterval: 300 shadeHover: false shadeHoverInterval: 250 separateScreenFocus: false placement: 4 focusPolicyIsReasonable: true borderSnapZone: 10 windowSnapZone: 10 centerSnapZone: 0 snapOnlyWhenOverlapping: false rollOverDesktops: true focusStealingPreventionLevel: 2 legacyFullscreenSupport: false operationTitlebarDblClick: 5000 operationMaxButtonLeftClick: 5000 operationMaxButtonMiddleClick: 5015 operationMaxButtonRightClick: 5014 commandActiveTitlebar1: 0 commandActiveTitlebar2: 30 commandActiveTitlebar3: 2 commandInactiveTitlebar1: 4 commandInactiveTitlebar2: 30 commandInactiveTitlebar3: 2 commandWindow1: 7 commandWindow2: 8 commandWindow3: 8 commandWindowWheel: 31 commandAll1: 10 commandAll2: 3 commandAll3: 14 keyCmdAllModKey: 16777251 showGeometryTip: false condensedTitle: false electricBorderMaximize: true electricBorderTiling: true electricBorderCornerRatio: 0.25 borderlessMaximizedWindows: false killPingTimeout: 5000 hideUtilityWindowsForInactive: true inactiveTabsSkipTaskbar: false autogroupSimilarWindows: false autogroupInForeground: true compositingMode: 1 useCompositing: true compositingInitialized: true hiddenPreviews: 1 glSmoothScale: 2 xrenderSmoothScale: false maxFpsInterval: 16666666 refreshRate: 0 vBlankTime: 6000000 glStrictBinding: true glStrictBindingFollowsDriver: true glCoreProfile: false glPreferBufferSwap: 101 glPlatformInterface: 1 windowsBlockCompositing: true Screen Edges ============ desktopSwitching: false desktopSwitchingMovingClients: false cursorPushBackDistance: 1x1 timeThreshold: 150 reActivateThreshold: 350 actionTopLeft: 0 actionTop: 0 actionTopRight: 0 actionRight: 0 actionBottomRight: 0 actionBottom: 0 actionBottomLeft: 0 actionLeft: 0 Screens ======= Multi-Head: no Active screen follows mouse: yes Number of Screens: 3 Screen 0: --------- Name: DP-1 Geometry: 1920,0,1920x1200 Refresh Rate: 59.9502 Screen 1: --------- Name: DP-3 Geometry: 0,0,1920x1080 Refresh Rate: 60 Screen 2: --------- Name: DP-2 Geometry: 3840,0,1920x1080 Refresh Rate: 60 Compositing =========== Compositing is active Compositing Type: OpenGL OpenGL vendor string: nouveau OpenGL renderer string: Gallium 0.4 on NVE7 OpenGL version string: 3.0 Mesa 13.0.4 OpenGL platform interface: GLX OpenGL shading language version string: 1.30 Driver: Nouveau GPU class: Unknown OpenGL version: 3.0 GLSL version: 1.30 Mesa version: 13.0.4 X server version: 1.19.1 Linux kernel version: 4.8.2 Direct rendering: Requires strict binding: yes GLSL shaders: yes Texture NPOT support: yes Virtual Machine: no OpenGL 2 Shaders are used Painting blocks for vertical retrace: no Loaded Effects: --------------- zoom slidingpopups kwin4_effect_login screenshot kwin4_effect_windowaperture minimizeanimation kwin4_effect_translucency flipswitch desktopgrid coverswitch colorpicker kwin4_effect_fade kwin4_effect_morphingpopups kwin4_effect_maximize presentwindows kwin4_effect_dialogparent highlightwindow blur contrast startupfeedback screenedge kscreen Currently Active Effects: ------------------------- blur contrast Effect Settings: ---------------- zoom: zoomFactor: 1.2 mousePointer: 0 mouseTracking: 0 enableFocusTracking: false followFocus: true focusDelay: 350 moveFactor: 20 targetZoom: 1 slidingpopups: fadeInTime: 150 fadeOutTime: 250 kwin4_effect_login: screenshot: kwin4_effect_windowaperture: minimizeanimation: kwin4_effect_translucency: flipswitch: tabBox: false tabBoxAlternative: true duration: 200 angle: 30 xPosition: 0.33000001311302185 yPosition: 1 windowTitle: true desktopgrid: zoomDuration: 300 border: 10 desktopNameAlignment: 0 layoutMode: 0 customLayoutRows: 2 usePresentWindows: true coverswitch: animationDuration: 200 animateSwitch: true animateStart: true animateStop: true reflection: true windowTitle: true zPosition: 900 primaryTabBox: true secondaryTabBox: false colorpicker: kwin4_effect_fade: kwin4_effect_morphingpopups: kwin4_effect_maximize: presentwindows: layoutMode: 0 showCaptions: true showIcons: true doNotCloseWindows: false ignoreMinimized: false accuracy: 20 fillGaps: true fadeDuration: 150 showPanel: false leftButtonWindow: 1 rightButtonWindow: 2 middleButtonWindow: 0 leftButtonDesktop: 2 middleButtonDesktop: 0 rightButtonDesktop: 0 kwin4_effect_dialogparent: highlightwindow: blur: blurRadius: 12 cacheTexture: true contrast: startupfeedback: type: 1 screenedge: kscreen:
The effects were implemented on a two screen system. I doubt they can work on a three screen system.
This issue report is quite old. Can you please confirm, that it still persists with KDE 5.23?
Well, 5.23 removed cover and flip switch, so I'd say "no" :-/