Created attachment 123202 [details]
gap between window and content visible

SUMMARY

When using fractional scaling (e.g. 1.25) on Wayland one can notice a gap between the window content and the window decoration. Comparable to what we always had when enabling wobbly windows.


STEPS TO REPRODUCE
1. Use Wayland
2. Use fractional scaling of 1.25
3. Use window decoration borders

OBSERVED RESULT

Gap between window content and window decoration (see screenshot)

EXPECTED RESULT

Properly rendered window

ADDITIONAL INFORMATION

Version
=======
KWin version: 5.17.80
Qt Version: 5.13.1
Qt compile version: 5.13.1
XCB compile version: 1.13

Operation Mode: Xwayland

Build Options
=============
KWIN_BUILD_DECORATIONS: yes
KWIN_BUILD_TABBOX: yes
KWIN_BUILD_ACTIVITIES: yes
HAVE_DRM: yes
HAVE_GBM: yes
HAVE_EGL_STREAMS: yes
HAVE_X11_XCB: yes
HAVE_EPOXY_GLX: yes
HAVE_WAYLAND_EGL: yes

X11
===
Vendor: The X.Org Foundation
Vendor Release: 11906000
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: 
Plugin recommends border size: None
Blur: 0
onAllDesktopsAvailable: true
alphaChannelSupported: true
closeOnDoubleClickOnMenu: false
decorationButtonsLeft: 0, 2
decorationButtonsRight: 6, 3, 4, 5
borderSize: 3
gridUnit: 12
font: Noto Sans,10,-1,5,50,0,0,0,0,0,Regular
smallSpacing: 3
largeSpacing: 12

Platform
==========
Name: DRM
Active: true
Atomic Mode Setting: true
Using EGL Streams: false

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
rollOverDesktops: true
focusStealingPreventionLevel: 1
operationTitlebarDblClick: 5000
operationMaxButtonLeftClick: 5000
operationMaxButtonMiddleClick: 5015
operationMaxButtonRightClick: 5014
commandActiveTitlebar1: 0
commandActiveTitlebar2: 28
commandActiveTitlebar3: 2
commandInactiveTitlebar1: 4
commandInactiveTitlebar2: 28
commandInactiveTitlebar3: 2
commandWindow1: 7
commandWindow2: 8
commandWindow3: 8
commandWindowWheel: 28
commandAll1: 10
commandAll2: 3
commandAll3: 14
keyCmdAllModKey: 16777251
showGeometryTip: true
condensedTitle: false
electricBorderMaximize: true
electricBorderTiling: true
electricBorderCornerRatio: 0.25
borderlessMaximizedWindows: false
killPingTimeout: 5000
hideUtilityWindowsForInactive: true
compositingMode: 1
useCompositing: true
hiddenPreviews: 2
glSmoothScale: 2
xrenderSmoothScale: false
maxFpsInterval: 16666666
refreshRate: 0
vBlankTime: 6000000
glStrictBinding: false
glStrictBindingFollowsDriver: true
glCoreProfile: false
glPreferBufferSwap: 101
glPlatformInterface: 2
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:  no
Number of Screens: 1

Screen 0:
---------
Name: LG Display eDP-1-unknown
Geometry: 0,0,1536x864
Scale: 1.25
Refresh Rate: 60.042


Compositing
===========
Compositing is active
Compositing Type: OpenGL
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) HD Graphics 5500 (Broadwell GT2) 
OpenGL version string: 3.0 Mesa 19.0.8
OpenGL platform interface: EGL
OpenGL shading language version string: 1.30
Driver: Intel
GPU class: Unknown
OpenGL version: 3.0
GLSL version: 1.30
Mesa version: 19.0.8
Linux kernel version: 4.15
Direct rendering: Requires strict binding: no
GLSL shaders:  yes
Texture NPOT support:  yes
Virtual Machine:  no
OpenGL 2 Shaders are used
Painting blocks for vertical retrace:  no

Loaded Effects:
---------------
zoom
trackmouse
touchpoints
thumbnailaside
kwin4_effect_morphingpopups
kwin4_effect_login
kwin4_effect_logout
kwin4_effect_frozenapp
kwin4_effect_maximize
kwin4_effect_fadingpopups
kwin4_effect_translucency
kwin4_effect_fade
kwin4_effect_dialogparent
kwin4_effect_windowaperture
kwin4_effect_squash
slidingpopups
slide
screenshot
flipswitch
desktopgrid
cube
coverswitch
colorpicker
presentwindows
highlightwindow
blur
contrast
windowgeometry
startupfeedback
screenedge
kscreen
invert

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

trackmouse:
modifiers: 335544320
mousePolling: true

touchpoints:
lineWidth: 1
ringLife: 300
ringSize: 20
ringCount: 2

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

kwin4_effect_morphingpopups:
isActiveFullScreenEffect: false

kwin4_effect_login:
isActiveFullScreenEffect: false

kwin4_effect_logout:
isActiveFullScreenEffect: false

kwin4_effect_frozenapp:
isActiveFullScreenEffect: false

kwin4_effect_maximize:
isActiveFullScreenEffect: false

kwin4_effect_fadingpopups:
isActiveFullScreenEffect: false

kwin4_effect_translucency:
isActiveFullScreenEffect: false

kwin4_effect_fade:
isActiveFullScreenEffect: false

kwin4_effect_dialogparent:
isActiveFullScreenEffect: false

kwin4_effect_windowaperture:
isActiveFullScreenEffect: false

kwin4_effect_squash:
isActiveFullScreenEffect: false

slidingpopups:
slideInDuration: 150
slideOutDuration: 250

slide:
duration: 500
horizontalGap: 45
verticalGap: 20
slideDocks: false
slideBackground: true

screenshot:

flipswitch:
tabBox: false
tabBoxAlternative: false
duration: 200
angle: 30
xPosition: 0.33000001311302185
yPosition: 1
windowTitle: true

desktopgrid:
zoomDuration: 300
border: 10
desktopNameAlignment: 0
layoutMode: 0
customLayoutRows: 2
usePresentWindows: true

cube:
cubeOpacity: 0.800000011920929
opacityDesktopOnly: false
displayDesktopName: true
reflection: true
rotationDuration: 500
backgroundColor: #000000
capColor: #0000ff
paintCaps: true
closeOnMouseRelease: false
zPosition: 100
useForTabBox: false
invertKeys: false
invertMouse: false
capDeformationFactor: 0
useZOrdering: false
texturedCaps: false

coverswitch:
animationDuration: 200
animateSwitch: true
animateStart: true
animateStop: true
reflection: true
windowTitle: true
zPosition: 900
primaryTabBox: false
secondaryTabBox: false

colorpicker:

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

highlightwindow:

blur:

contrast:

windowgeometry:
handlesMoves: true
handlesResizes: true

startupfeedback:
type: 1

screenedge:

kscreen:

invert: