And remove qt5ct (tool to configure qt apps in gtk environments)
sudo pacman -R qt5ct
As I see this is a package to make qt apps work with gtk. I think this setting should be done in case the gtk DE is removed and only Plasma remains.
Should something special be done in order to have both DEs in parallel and to ensure good functionality of Qt apps in XFCE?
In general, you should not use multiple DEs on the same installation because that usually causes problems.
qt5ct and qt6ct are for when you are using KDE/Qt-based apps in a GTK-based DE or setup. Since you would still have XFCE, you may actually need it, as your KDE theme settings may not apply while using XFCE.
But yes, if you decide to use only Plasma, then removing that app would be recommended.
Main thing:
Don’t use KDE apps in your XFCE environment and vice versa. This is specific to their individual system settings and other related apps; not actual apps like text editors, blender, etc.
So, don’t open KDE system settings while you’re in XFCE, and don’t open XFCE Settings while in KDE.
Another thing is to set the GTK theme in KDE System Settings. Can’t remember where to find it. Someone will maybe chime in and tell/show you where it is.
