GTK3 overlay scrollbars

I do not particularly like the behaviour of GTK3 applications. Among the things that annoy me are the scroll bars. I want to make them always visible, by removing the dynamic show/hide. I searched a bit and found this instructions at the excellent Arch Linux wiki.

I boot my system in run level 3, so I just opened ~/.xinitrc and added the following before starting the Xfce desktop environment:

export GTK_OVERLAY_SCROLLING=0

########################################################################
##  Start xfce Desktop Environment                                    ##
########################################################################
if [ -z "$DESKTOP_SESSION" -a -x /usr/bin/ck-launch-session ]; then
  exec ck-launch-session dbus-launch --exit-with-session /usr/bin/startxfce4
else
  exec dbus-launch --exit-with-session /usr/bin/startxfce4
fi

Then, I created ~/.config/gtk-3.0/gtk.css and added the following:

undershoot.top, undershoot.right, undershoot.bottom, undershoot.left { background-image: none; }

Rebooted and setting are now applied.