The appearance settings of xfce seem only affect gtk2 applications. Is it possible to change gtk-3 theme on xfce, by using a GUI tool (basic preview)?
1 Answer
My personal recommendation is to use the clearlooks-phenix-theme package (from the official Debian archive) and then select it in the standard XFCE's theme picker.
The upside of this theme package is that it combines theme engines both for GTK2 and GTK3 applications—making them look sort of uniform. Since the archive contains both GTK2 and GTK3 apps (and this situation, due to certain frictions certain group of developers have with GTK3 fast pace of changes, is unlikely to be completely resolved soon) this package solves the issue of applications using different versions of the GTK toolking looking differently.
The downside is that if you don't like the Clearlooks theme itself (it was the default back in the later GNOME 2 days) you won't like this one either.
Alternatively, I'm afraid, you'd need to manually edit the user's GTK3 configuration file to tweak the theme used for GTK3 apps.
Adwaitais the only "complete" theme included by default, which supports both GTK+ 2 and GTK+ 3 applications. Else, you will need to install other supported themes from the repository.