After upgrading to Kubuntu 15.10 I started noticing issues on some applications. I don't know exactly how to describe it, nor which component is really the one bugged, so I chose kwin. This *might be* related to the use of an external monitor, or to suspend/resume. Hard to tell because it starts happening after some time. The only way to fix it is to reboot the computer. I'm attaching a screenshot to try to illustrate what's going on. On the left side, is KDialog, that shows up when hitting Ctrl + O in Chromium (the "Open" dialog for Kate, doesn't do this...) On the right side of the screenshot, you can see Skype (I have blurred the names which are barely readable, but the rest is just how it is being rendered, with names showing up in front of others). After a cold restart, everything works just right. But after a while, it starts behaving like this... Reproducible: Sometimes
Created attachment 95213 [details] Rendering issues
please see whether restarting the compositor (SHIFT+Alt+F12, twice) "fixes" it, whether it also occurs while the compositor is deactivated and in any case attach the output of "qdbus org.kde.KWin /KWin supportInformation" (with compositing enabled)
I confirm this problem is happened always. It's annoying and occurs in different apps like KDialog and KColorChooser, ...etc I have tried (SHIFT+Alt+F12, twice) but it doesn't solve it!
> ... whether it also occurs while the compositor is deactivated and in any case attach the output > of "qdbus org.kde.KWin /KWin supportInformation" (with compositing enabled) Looking at the screenshot, this however looks like an issue reported on the forum and is not related to the compositor or KDE at all, but caused by OpenJDK and usually lasts until the Java client is closed (or the session restarted at least) - does that match your situation?
Closing/restarting java apps seems to solve the problem.
It's apparently not a problem with oracles JDK. I don't know what java does or how it screws font rendering (notably in Qt5 clients which afaiu use a local rasterizer), but it's not a KWin bug at all.
Well, I was using PyCharm when having these issues... wen't back to kate for performance issues (:P) and now, I no longer see them, so it does sound like Java is somehow messing with it. However, some points: 1) This was not happening in KDE 4 2) AFAIK this does not happen with other window managers 3) This seems to only happen in non-kde applications (Chrome, Skype, etc), and does not happen in Kate, Konsole, etc... I agree this is not a *bug in kwin* but is there a way this could be addressed so it doesn't happen?
(In reply to Franco Pellegrini from comment #7) > 2) AFAIK this does not happen with other window managers You mean if you install and run "openbox --replace &", this does *not* happen? (Otherwise it's probably related to the desktop environment, because Chrome should use the gtk file dialogs in gnome/xcfe/... and afair Qt used a different rendering mechnism with the gtk+ integration) > 3) This seems to only happen in non-kde applications (Chrome, Skype, etc), > and does not happen in Kate, Konsole, etc... Could mean that this rather affects Qt4? > I agree this is not a *bug in kwin* but is there a way this could be > addressed so it doesn't happen? OpenJDK: because it does something stupid xft/freetype/fontconfig: because it's not robust against something stupid
(In reply to Thomas Lübking from comment #8) > (In reply to Franco Pellegrini from comment #7) > > 2) AFAIK this does not happen with other window managers > > You mean if you install and run "openbox --replace &", this does *not* > happen? > > (Otherwise it's probably related to the desktop environment, because Chrome > should use the gtk file dialogs in gnome/xcfe/... and afair Qt used a > different rendering mechnism with the gtk+ integration) Well, I have a friend using PyCharm as well, under Ubuntu 15.10 (using Unity) and he has not seen this kind of behavior. Furthermore, I was not seeing it before upgrading to kubuntu 15.10. This seems to only happen under KDE5. I will install openbox and when I see this again, will run that command and see what happens. > > > 3) This seems to only happen in non-kde applications (Chrome, Skype, etc), > > and does not happen in Kate, Konsole, etc... > > Could mean that this rather affects Qt4? How can I tell? > > > I agree this is not a *bug in kwin* but is there a way this could be > > addressed so it doesn't happen? > > OpenJDK: because it does something stupid > xft/freetype/fontconfig: because it's not robust against something stupid Yeah, my question is, can this be improved to live along retarded software? :)
(In reply to Franco Pellegrini from comment #9) > Well, I have a friend using PyCharm as well, under Ubuntu 15.10 (using > Unity) and he has not seen this kind of behavior. That's no srtong indication, because you friend might simply be using a different version or vendor (oracle) of JDK > Furthermore, I was not seeing it before upgrading to kubuntu 15.10. I assume that included an OpenJDK update? ;-) > > Could mean that this rather affects Qt4? > How can I tell? ldd `which skype` (uses Qt4 on archlinux, I'm not sure there even is a Qt5 version) > Yeah, my question is, can this be improved to live along retarded software? Hard to say w/o knowing the bug. If it's like JDK says "oh, nice! a glyph cache. I'm gonne nuke that!" the answer will be rather "no" :-( Let's first see whether this is related to either the Window Manger (openbox --replace) or the Desktop Environment (you should be able to log into a plain openbox session) If not, the next best thing would be to file a bug against OpenJDK. It might be interesting whether changing the Qt4 graphicssystem skype -graphicssystem raster vs. skype -graphicssystem native has any impact (notice that I actually do not know whether esp. skype honors the switch, you might have to fall back to some other Qt4 client to test this)
Created attachment 95589 [details] Openbox also has the issue When I started to see the problem, I opened a konsole, and ran openbox --replace & The problem is still present. On the right you can see an Open dialog for Chromium, and on the left, an open dialog for kate. The one for kate works fine, the one for Chromium not.
Smells like Qt4 related, I couldn't reproduce this with openjdk 7.u91_2.6.3 & jedit, tried plain Qt4 client on raster and native graphicssystem. => your openjdk version?
openjdk-7-jre_7u85-2.6.1-5_amd64 and pycharm community edition 5.0.1 It doesn't happen *right away*. I keep it opened and use it, and after a while, It randomly starts happening. Couldn't find a concrete way of reproducing it yet.
Nope, not reproduced in hours... maybe it's fixed in newer JDKs?