[kde-linux] OpenGL & fonts flickering

Thomas Bettler thomas.bettler at gmail.com
Wed Sep 20 15:33:45 UTC 2006

I don't know how to solve this issue neither hwhere to report a bug on it so I 
try it here, hope you can help my getting more details, that I can fill a bug 

Running some OpenGL application (i.e. 3ddesk, kaffeine opengl driver) makes 
the fonts (i.e. KDE panel clock, menus, desktop icon names) but only the 
fonts flicker like crazy.
Stopping the OpenGL at any point, sometimes the fonts are redrawn, sometimes 
they are not (just blank). 
Taking a screenshot doesn't redraw the fonts on screen, despite the screenshot 
has sane font drawing.

I run Xorg with radeon driver (have a radeon r100 card) and changing the 
option "PageFlip" to "false" (see radeon 4) makes this issue disappear, but 
instead the rendering is real sloooow.

So know the fonts flickering is obviously related to page flipping.

To find out wheater the issue is related to Qt/KDE or Xorg I tried other 
toolkits/applications. GIMP doesn't show this bevaviour, so I guess it's a 
matter of Qt/KDE.

Most probably the issue is located in Qt, as a Qt only app (qbankmanager) 
showed the same effects.

I guess the flickering itself is not an issue but only an effect. I suspect 
this, because sometimes the fonts are correctly drawn, sometimes not. I guess 
the real issue possibly is related to double buffering, font caching, 
redrawing fonts or something similar.

So should I contact Trolltech, or do you think we could solve this bug 

Thank you a lot for any hints helping to locate the issue.

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