Created attachment 49375 [details]
bad screenshot of the problem

as i can't make a screenshot using a desktop tool as the window get redrawn at the same moment i start the tool or trying to make a screenshot, i have to use an external cam.

with disabled desktop effects this doesn't seems to exist. I will try out to find if every kwin desktop effect is producing this really unhealthy bug.
(this doesn't causes data lose, but health risks ;) )

I confirm this. NVidia 8600M here, this bug exists for long time and i've tried many versions of NVidia proprietary drivers.

This accurs only when composition is active.
My composition settings:
- OpenGL
- Preview only for visible windows
- Suspend desktop effects for fullscreen windows
- OpenGL mode: texture from pixmap
- Twolinear filter
- Direct rendering
- VSync enabeled

the taskbar preview popup?

I don't understand this question. Do you want screenshot?

means "what can be seen on OP scrot looks alot like it could have been triggerend by the window preview that appears when you hover a taskbar entry"...

this would be triggered by either the "highlight window" but more likely the "sliding popup" effect...

No, this happens randomly when clicking inside application.
I haven't noticed anything that could be connected to these two effect.
The scenario is simple: just use an application an wait for it to disappear. I'll try to use some desktop recording software to show this.

please attach /etc/X11/xorg.conf (if present) and /var/log/Xorg.0.log

Created attachment 53173 [details]
my xorg.conf directory

I use OpenSuse factory, so I don't have xorg.conf file but xorg.conf.d directory

Created attachment 53174 [details]
log file

I think I can reproduce it on demand now. This is how I do it:
1. set up some virtual desktops
2. open Firefox on one (fullscreen)
3. open Akregator on another one (right half of screen)
4. go to firefox screen (i use keyboard shortcuts, this works with clicking on pager too)
5. click on firefox
6. go to akregator screen
7. click on akregator
8. click on plasma desktop
9. go to firefox screen
10. click on firefox, but in place where akregator window is (right half of firefox window)
11. right half of firefox window dissapears


Clickng on plasma desktop is essential here.

not reproducable here.
is it related to firefox (version?) / akregator (didn't have, tried with kmail)

also what effect plugins do you use*? "slide back"?

*fast dump:
grep -iE 'kwin4_effect_.*Enabled=true' `kde4-config --path config | cut -d":" -f1`/kwinrc | sed -e 's/kwin4_effect_//g; s/Enabled=true//g'

blur
boxswitch
dashboard
desktopgrid
dialogparent
diminactive
dimscreen
glide
highlightwindow
login
logout
magiclamp
presentwindows
screenshot
shadow
slide
slideback
slidingpopups
startupfeedback
taskbarthumbnail
translucency
wobblywindows





I think it is related to Firefox. As soon as firefox started it happened.
I'll try to disable sideback plugin and check then.

Removed slideback effect. Now everything is OK.

Created attachment 53207 [details]
patch attempt

ok, i'm probably too retarded to reproduce this, but i've a distant idea what casues this.

attached is a patch that might fix/workaround the assmumed issue.
if anyone who encounters this could please test the patch and report that would help alot. thanks.

This works for me.
Thank you very much:)

http://svn.reviewboard.kde.org/r/5783/

SVN commit 1197040 by luebking:

Fix #245372 (clipping error on VD change)

BUG: 245372


 M  +12 -12    slideback.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=1197040

*** Bug 257522 has been marked as a duplicate of this bug. ***

SVN commit 1200083 by luebking:

backporting r1197040 "clipping error on VD change"
CCBUG: 245372


 M  +12 -12    slideback.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=1200083