SUMMARY After installing plasma-desktop 5.14 and startkde gtk dark color themes on XFCE getting screwed. After first usage of kde plasma desktop you will have wrong dark theme colors while using XFCE with the same ~/.config directory. If you try to reuse XFCE with a dark theme you will get grey fonts on a grey menu nearly unreadable. Also tab widgets will getting grey STEPS TO REPRODUCE 1. install xfce with an adwaita dark theme 2. install plasma-desktop with breeze-dark and maybe oxygen design 3. restart X11 with XFCE and watch what you have got OBSERVED RESULT If you try to reuse XFCE with a dark theme after setting up and starting plasma-desktop with a dark theme you will get grey fonts on a grey menues nearly unreadable. Also tab widgets will getting grey. EXPECTED RESULT Untouched dark GTK themes! SOFTWARE/OS VERSIONS Linux/KDE Plasma: Arch Linux with plasma-desktop 5.14 ADDITIONAL INFORMATION Someone observed the same problem two years ago on Fedora 25: http://stevenrosenberg.net/blog/linux/2016_1201_kde_plasma_screwed_up_everything You can reset the dark XFCE color themes if you delete ~/.config
Sorry, can not reproduce this problem on a new installed Arch Linux system. I have no idea which package on my old Arch Linux setup overwrite the gtk theming. First I thought about dconf but dconf -reset -f /gnome and /gtk does not help.
Thanks, let us know if you ever find a reproducible test case!
I found the solution to remove the style problems between KDE and XFCE on my old Arch Linux system I simply used: rm -rf ~/.gtkrc-2.0 and that helped to make the theming between both desktop environments consistent again.