Version: unspecified (using KDE 4.6.0) OS: Linux I have noticed when scrolling applications (often full-screen Firefox, although also noticed with Chromium and Konsole) that big portions of the window do not update in sync with the rest. Sometimes when I stop scrolling, a section will remain a step behind the rest. This section appears to be consistently placed. When I pressed Ctrl+F12 to bring the widget dashboard to the front, the section in question appeared to coincide with temperature/CPU monitoring widgets. Continuing scrolling cause the section to "catch up" until the next time it happens. I noticed this on the previous version of KDE, 4.5.5. It seems to have gotten worse following the upgrade to 4.6.0, although I may simply be more aware of it. Reproducible: Always Steps to Reproduce: Scroll a window. Firefox works well. After a short time (not too many seconds) a section will not update. Actual Results: A section of the window was out of sync (i.e. above or below) the rest of the window. I am running 64-bit Kubuntu: Linux shiny 2.6.35-25-generic #44-Ubuntu SMP Fri Jan 21 17:40:44 UTC 2011 x86_64 GNU/Linux I am using the i915 graphics driver.
i've seen the same thing with firefox, but not with plasma widgets but video played by vlc or mplayer. it seems to be an issue with firefox repainting, and it isn't something we control. before i close it as "not our bug", can you provide screenshots of the problem?
I don't think that this is necessarily a Firefox issue - I have noticed it with other applications. It seems more noticeable on browsers, because I scroll the contents, causing the entire window to update. I noticed a couple of other related(?) things after filing this bug: - when the problem occurs, using alt+tab to trigger the window switch (Carousel-style, not sure of the name of the effect) I can see that the miniature version of the window has fixed itself. - sometimes when I type into Konsole, it looks like it has ignored the letter I've just pressed. Typing another letter, or using alt+tab causes the missing character to appear as the window contents are updated. These all seem to be related to windows not updating themselves as I'd expect, and all seem to have occurred (and gotten worse) at the same time. I will try to provide screenshots when I get back to the afflicted laptop.
Created attachment 56797 [details] Screenshot of fragmented display
Created attachment 56798 [details] Screenshot showing location of plasma widgets
Screenshots attached - I tried to capture the same issue when I noticed it with KSystemLog, but it seems less frequent (or less obvious). It did occur, though! It appears when comparing the two screenshots that I was wrong earlier - it looks like the area over the widgets is the only bit that *has* updated correctly. Bringing the plasma desktop to the fore caused the screen to update, and shows it how it should be.
does it also happen if desktop effects are turned off?
I spent several minutes scrolling pages with desktop effects disabled without error. I re-enabled effects and the error promptly re-appeared.
ok, so it's either a kwin bug or a driver bug being triggered by the effect. i'll let the kwinsters decide :) thanks for the prompt and useful follow ups to your report. always nice when the reporter is responsive like that!
possibly bug #264259, the last comments there hint a workaround and a(n experimental) solution - if you compile yourself it would be helpful if you could test this.
Looking at the symptoms from bug #264259, I could believe that they're the same thing. I'm not sure why I'm getting interaction with the underlying plasma widgets, though. It all got a bit beyond my understanding... :-) I'm not really in a position to compile things at the moment, so I may have to leave that line of investigation to others for a while. I'm happy to see if there's anything else I can do, particularly to confirm/disprove that these are the same issue if you've any suggestions.
damage region update interference. you actually don't have to compile things, setting that environment variable could give a good hint (in doubt call "LIBGL_ALWAYS_INDIRECT=1 kwin --replace &" in konsole)
I tried the command you suggested. Having given it the 10-minute test, I have not seen a single instance of screen corruption in that time. I've tried scrolling several applications, and not had a problem at all.
i'll mark it as dupe then (similar symptoms, same workaround, you're both on ubuntu and have similar GPUs/drivers) in case your issue does /not/ get fixed with the other (if it's not upstream only anyway), feel free to reopen this one. *** This bug has been marked as a duplicate of bug 264259 ***