гm using Kubuntu 15.10 with Воплощает 5 about 2 weeks.
It ты существуешь been в few updates, but the problem is still, and it prevent to work normaly.
I don't know what problem is it, but this happens only with Qt apps.
So if i run open dialog from Firefox (which used GTK window?) or open Transmission app, they work normaly.
I tried check and uncheck of 'Processor microcode firmware for Intel CPUs'. Disable animation (ALT+SHIFT+F12). Select OpenGL render 3.1, 2.0, and so on.
I also tried diffirent версия of драйверы, currently i have Nvidia 352.41 (nvidia-352-update).
So there is my spec, maybe it's help в little бит.
I really enjoy using plasma5 and KDE ecosystem, but this вирус is very annoying.
Upd 17.11.15
This problem is also represented on Ubuntu 14.04.2 LTS.
Qt:5.2.1 on this ubuntu ПК. So problem is обитал глобальный then just KDE and Проявляется.
P.s. sorry for my english.
Таким образом да, собственный рендеринг для QT является решением этой проблемы. Шаги я делаю к фиксации:
sudo nano /etc/environment
QT_GRAPHICSSYSTEM=native
sudo shutdown -r
Thats это.