Created attachment 91547 [details]
Examplified glitch

could you please provide the output of:
qdbus org.kde.KWin /KWin supportInformation

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: 5.2.1
Qt Version: 5.4.1

Operation Mode: X11 only

Decoration
==========
Plugin: org.kde.breeze
Theme: 
Blur: 0
onAllDesktopsAvailable: false
alphaChannelSupported: true
closeOnDoubleClickOnMenu: false
decorationButtonsLeft: 0
decorationButtonsRight: 3, 4, 5
borderSize: 2
gridUnit: 10
font: Ubuntu,9,-1,5,52,0,0,0,0,0
smallSpacing: 2
largeSpacing: 10

Options
=======
focusPolicy: 0
nextFocusPrefersMouse: false
clickRaise: true
autoRaise: false
autoRaiseInterval: 0
delayFocusInterval: 0
shadeHover: true
shadeHoverInterval: 250
separateScreenFocus: false
placement: 4
focusPolicyIsReasonable: true
borderSnapZone: 10
windowSnapZone: 10
centerSnapZone: 0
snapOnlyWhenOverlapping: false
showDesktopIsMinimizeAll: 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
unredirectFullscreen: false
glSmoothScale: 2
colorCorrected: false
xrenderSmoothScale: false
maxFpsInterval: 16666666
refreshRate: 0
vBlankTime: 6000000
glStrictBinding: true
glStrictBindingFollowsDriver: true
glCoreProfile: true
glPreferBufferSwap: 101
glPlatformInterface: 1

Screen Edges
============
desktopSwitching: false
desktopSwitchingMovingClients: false
cursorPushBackDistance: 1x1
timeThreshold: 150
reActivateThreshold: 350
actionTopLeft: 0
actionTop: 0
actionTopRight: 2
actionRight: 0
actionBottomRight: 0
actionBottom: 0
actionBottomLeft: 0
actionLeft: 0

Screens
=======
Multi-Head: no
Active screen follows mouse:  yes
Number of Screens: 1
Screen 0 Geometry: 0,0,1366x768

Compositing
===========
Compositing is active
Compositing Type: OpenGL
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Sandybridge Mobile x86/MMX/SSE2
OpenGL version string: 3.3 (Core Profile) Mesa 10.4.4
OpenGL platform interface: GLX
OpenGL shading language version string: 3.30
Driver: Intel
GPU class: SandyBridge
OpenGL version: 3.3
GLSL version: 3.30
Mesa version: 10.4.4
X server version: 1.17.1
Linux kernel version: 3.19.1
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:
---------------
thumbnailaside
slidingpopups
kwin4_effect_login
wobblywindows
slide
screenshot
minimizeanimation
kwin4_effect_translucency
glide
kwin4_effect_scalein
flipswitch
desktopgrid
kwin4_effect_fade
kwin4_effect_maximize
presentwindows
highlightwindow
kwin4_effect_dialogparent
blur
contrast
logout
dashboard
startupfeedback
screenedge
kscreen

Currently Active Effects:
-------------------------
blur
contrast
startupfeedback

Effect Settings:
----------------
thumbnailaside:
maxWidth: 200
spacing: 10
opacity: 0.5
screen: -1

slidingpopups:
fadeInTime: 30
fadeOutTime: 50

kwin4_effect_login:

wobblywindows:
stiffness: 0.15
drag: 0.8
moveFactor: 0.1
xTesselation: 20
yTesselation: 20
minVelocity: 0
maxVelocity: 1000
stopVelocity: 0.5
minAcceleration: 0
maxAcceleration: 1000
stopAcceleration: 0.5
moveEffectEnabled: true
openEffectEnabled: false
closeEffectEnabled: false
moveWobble: true
resizeWobble: true

slide:

screenshot:

minimizeanimation:

kwin4_effect_translucency:

glide:
duration: 70
effect: 0
angle: -90

kwin4_effect_scalein:

flipswitch:
tabBox: false
tabBoxAlternative: false
duration: 40
angle: 30
xPosition: 0.330000013113022
yPosition: 1
windowTitle: true

desktopgrid:
zoomDuration: 60
border: 10
desktopNameAlignment: 0
layoutMode: 0
customLayoutRows: 2
usePresentWindows: true

kwin4_effect_fade:

kwin4_effect_maximize:

presentwindows:
layoutMode: 0
showCaptions: true
showIcons: true
doNotCloseWindows: false
ignoreMinimized: false
accuracy: 20
fillGaps: true
fadeDuration: 30
showPanel: false
leftButtonWindow: 1
rightButtonWindow: 2
middleButtonWindow: 0
leftButtonDesktop: 2
middleButtonDesktop: 0
rightButtonDesktop: 0

highlightwindow:

kwin4_effect_dialogparent:

blur:
blurRadius: 11
cacheTexture: true

contrast:

logout:
useBlur: true

dashboard:
brightness: 0.5
saturation: 0.5
blur: false

startupfeedback:
type: 1

screenedge:

kscreen:

bug #320892 ?
Try to disable the "sliding popups" effect in "kcmshell5 kwineffects" and see whether the issue remains.

indeed, it is gone now after deactivation of the sliding popups...

*** This bug has been marked as a duplicate of bug 320892 ***