also deb#837356

since gtk3 commit of...

commit 0f116135f4a5033ce4e9dfa19f10624701fa615c
Author: Matthias Clasen <mclasen@redhat.com>
Date:   Fri May 6 10:12:14 2016 -0400

    Avoid emitting ::style-set by name

    GtkStyle is deprecated, but we still emit ::style-set quite
    a bit, so lets at least not be slow while doing it.

docs say...

'GtkWidget::style-set has been deprecated since version 3.0 and should not be
used in newly-written code.

Use the “style-updated” signal'

and this code just came over from gtk2 without any thought about it at the
time, so change it over to the "style-updated" which makes everything happy
again

Change-Id: I9e920d2fb2d820ff1b1b5a9ecb228484df3d6146