pin johnb its only for Qt5-apps, it won't work on gtk-apps. Besides, do you want qt5ct or kvantum in charge?!
johnb qt5ct is like a lxappearance. you could choose what let's call it engine would do the theme for qt apps. inside the qt5ct you choose Kvantum as your theme engine. the you would run kvantummanager to choose you kvantum theme. 😃
pin johnb I see, I've only used xfce for sometime before jumping to awesomewm, which I still use, and spectrwm.