I am using i3wm on Ubuntu 15.10. I was wondering on how to change the QT5 theme? With old QT4 it was possible to change it with qt4-config. There is however no qt5-config as of yet. I have tried using qt-config-tool, but it segfaults on launch. There is also lxqt-config, but it is only in xenial repositories, and I need it for willy. So is there an elegant way to change QT5 themes with Ubuntu 15.10? Also, what is the package name of the KDE system settings, so that I try to apt-get it? Will it pull all of KDE to my system or just some qt libs?
The package/app you're looking for is qt5ct which is the new and much better version of the old qt(4)config for qt5.
With it you can customise almost every aspect of your qt5 apps. You can set fonts, icon theme, colour schemes and widget styles, other small interface feauters and Qt style sheets (qss) to be applied globally to all qt5 apps. And you can save your colour schemes with different names and easily change between them.