I'm using Kubuntu 15.10 with Plasma 5 about 2 weeks.
It has been a 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 version of drivers, currently i have Nvidia 352.41 (nvidia-352-update).
So there is my spec, maybe it's help a little bit.
- Kubuntu 15.10 (64-bit)
- KDE Plasma: 5.4.2
- Qt: 5.4.2
- Kernel: 4.2.0-18-generic
- Processor: 4 x Intel Core i5-4590 CPU @ 3.30GHz
- Memory: 8GB
- Video: Nvidia GeForce GTX970
I really enjoy using plasma5 and KDE ecosystem, but this bug is very annoying.
This problem is also represented on Ubuntu 14.04.2 LTS.
Qt:5.2.1 on this ubuntu PC. So problem is more global then just KDE and Plasma.
P.s. sorry for my english.