I have a problem with screen fonts in a KDE application running under Xfce.

I installed openSUSE 42.1 Leap with Xfce as DE.

I want to use some KDE applications or KDE-based applications under that desktop environment Xfce.

Particularly I'm interested in using Krusader. I installed Krusader (v 2.4.0-beta3) from repository. Additionally I installed 'some' KDE libraries and the KDE systemsettings package.
The info in 'Krusader > About' tells me: Running under KDE 4.14.10.

Krusader itself runs fine but it uses a default screen font for menus and panel tab titles (Sans) that doesn't match the default screen or system font used by Xfce throughout the rest of the system (Liberation Sans, 10pt). The font appears bold and not very smooth.

I want to force Krusader / KDE to use Liberation Sans as well for the menus etc. to align the appearance of Krusader with the rest of the system.

I tried to use KDE System Settings (package systemsettings): I can open the KDE System Settings dialog but I only get offered 4 items (Desktop > "Keyboard Shortcuts", Network > Settings, Network > Connections, System Settings > YaST). There is no item for fonts nor appearances.

I also tried to play with the settings in the ~/.kde4/share/config/kdeglobals config files, adding font and menuFont entries to the [General] section. But that didn't show any effect, neither directly nor after logout-relogin or system reboot.

How can I change the font that is used by Krusader for the menus and panel titles? Generally speaking: How can I set the screen fonts used by KDE applications under Xfce?

Any help appreciated... Many thanks!

you should also be offered a fontmanagement module, so am guessing you are missing a package try installing kdebase4-workspace-addons (for KDE4, would be plasma5-desktop in Plasma 5)

I would have thought you would be running under 5 in Leap

Many thanks for your help -- this did the job. Problem solved!
I installed kdebase4-workspace-addons as you recommended.

In fact, I didn't install before complete KDE on the system since I've chosen for Xfce as my desktop env. So I only installed some base KDE components during the install of Krusader in order to be able to use Krusader under Xfce.
I intentionally decided to use KDE4 because 'Plasma 5' still seems still too instable. I don't want to use KDE as my DE but only some KDE apps under my favorite DE Xfce.
However, apparently I didn't install all necessary KDE4 components at that time...

On the other hand: After installing package kdebase4-workspace-addons I got more entries in the KDE System Settings dialog under Xfce than I had before. Nevertheless, there is no fontmanagement module available. However, I found an icon 'Application Style' (Appearance) where I can set the style of Gnome/GTK applications. There I can choose a font. I set it to 'Liberation Sans 10pt'. Then logout - re-login, restarting Krusader... and: Bingo, the screen font of Krusader has changed to Liberation Sans!
Although I'm still wondering why the settings of 'style of Gnome/GTK application' has an effect on the way Krusader is displayed (hence a Qt application running under Xfce)???
So it solved the problem but I don't understand why...