I have been using Geany as my editor for years, and I'm used to the theme.

Recently I upgraded Geany to the latest version, and found that it has been using GTK-3 theme. I hate GTK-3 theme and want Geany to use GTK-2 theme. How may I make it?

My environment:

Archlinux with glibc 2.26-11 gtk2 2.24.32-1 gtk3 3.22.28-1

Xfce 4.12

Geany 1.33.0-2

(Also, I don't mind making all my apps using GTK-2 theme.)