I lost the thumbs in the tabbox. How can I get them back?

Do you see text, icons, black fields or nothing instead?

Text and icons.
An icon where the preview should have been, and a text (the window title) below.
The loss happened after using an external display.

Compositor suspended/deactivated?
To be sure, please post (in code tags) the output of
qdbus org.kde.KWin /KWin supportInformation

If not, the tabbox can be configured in "kcmshell5 kwintabbox".

Looks like compositing is off - how to turn it back on? I did NOT knowingly turn it off

Code: Select all

Version
=======
KWin version: 5.2.1
Qt Version: 5.4.1

Operation Mode: X11 only

Decoration
==========
Plugin: org.kde.kwin.aurorae
Theme: kwin4_decoration_qml_plastik
Blur: 1
onAllDesktopsAvailable: false
alphaChannelSupported: false
closeOnDoubleClickOnMenu: false
decorationButtonsLeft: 0, 2
decorationButtonsRight: 6, 3, 4, 5
borderSize: 2
gridUnit: 10
font: Oxygen-Sans,10,-1,0,50,0,0,0,0,0
smallSpacing: 2
largeSpacing: 10

Options
=======
focusPolicy: 0
nextFocusPrefersMouse: false
clickRaise: true
autoRaise: false
autoRaiseInterval: 0
delayFocusInterval: 0
shadeHover: false
shadeHoverInterval: 250
separateScreenFocus: false
placement: 4
focusPolicyIsReasonable: true
borderSnapZone: 10
windowSnapZone: 10
centerSnapZone: 0
snapOnlyWhenOverlapping: false
showDesktopIsMinimizeAll: false
rollOverDesktops: true
focusStealingPreventionLevel: 1
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: true
killPingTimeout: 5000
hideUtilityWindowsForInactive: true
inactiveTabsSkipTaskbar: false
autogroupSimilarWindows: false
autogroupInForeground: true
compositingMode: 1
useCompositing: false
compositingInitialized: false
hiddenPreviews: 1
unredirectFullscreen: false
glSmoothScale: 2
colorCorrected: false
xrenderSmoothScale: false
maxFpsInterval: 16666666
refreshRate: 0
vBlankTime: 6000000
glStrictBinding: true
glStrictBindingFollowsDriver: true
glCoreProfile: false
glPreferBufferSwap: 97
glPlatformInterface: 1

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:  no
Number of Screens: 1
Screen 0 Geometry: 0,0,1366x768

Compositing
===========
Compositing is not active

[anders@archie ~]$


... A secret - Alt + Shift + F12. I had to look this up in shortcuts kcm, no indication in kwin areas. I do not remember being alerted it was turned off, and was not alerted that it was set on when using that shortcut.

> useCompositing: false

The shortcut is hinted in the kcm where you can disable initial compositing.
This might have happened iplicitly for re-occurring crashes on startup (eg. due to a temporarily broken driver installation or similar)

run "kcmshell4 kwincompositing", resp. "kcmshell5 kwincompositing" on KDE 5

I am running kde5. Systemsettings is very confusing, kwin settings are spread ovre many sections. The module you mention does not appear to be in there. And it does not hint about any shortcuts here.

I tried to switch to EGL, but up to now, if compositing is off, the desktop is missing some shadows making stuff like krunner visible, apart from the window thumbs. If on, there are lots of crashing and freezing - sometimes, not always, but it does not feel safe. Maybe it will work with EGL.

You will find the compositing module under "Monitor and Video" (or "Screen and Video", I'm reading from the translated version in my language) in System Settings.

If the command doesn't spawn the dialog, it's either not installed (kcmshell5 might also be named kcmshell?) or the sycoca is dirty (I've some KDE4/5 inteference I assume and occasionally loose either) - in that case, run "kbuildsycoca5"