[Solved] Slow resizing for some apps under KDE4.

Question

I use KDE4 (with the default theme) and Radeon graphic card (free driver). My problem is that the resizing of some windows is really slow. The problem does not appear with the KDE QT applications, but mostly for some old apps. Claws-mail is particularly affected. I do not think it is really a driver problem because claws-mail is unaffected in other window manager (as the default one in Ubuntu, with the same driver) as well in more primitive window managers like icewm. Moreover, native KDE4  QT apps behave properly.
It seems that modern Qt apps redraw approximatively while the resizing and do a final, complete redraw when it is finished, so it is smooth. Claws-mail redraw every time and it's not smooth. However, with other window managers, claws-mail does not redraw at all while the resizing and redraw one time at the end which is less visually appealing, but nevertheless smooth (it was probably the old method); for some reason it redraw every time while the resizing in KDE4.
I am only guessing and have not been able to find a proper documentation nor any fix. Anyone can point me in the right direction?
Last edited by olive (2014-09-24 18:11:59)

Answer 1

I reply to my own post. The culprit was the oxygen GTK theme under KDE. Under KDE, change it to Raleigh with System Setting -> Application Appearance -> GTK and the problem is solved. I had a problem with bluegriffon (from the AUR) that crashes. It was suggested here that the oxygen GTK theme was the culprit: https://groups.google.com/forum/#!topic … Xb92OyWNj8 . Indeed, after changing the theme, no more crash, and as no more problem with resizing windows!. Strange bugs though, I would have thought of everything but the GTK theme ?!?