Comment # 2 on bug 994832 from Wolfgang Bauer

I think the problem is that Leap 42.1 shipped with and used BreezyGTK for GTK
applications on a KDE installation.
This has later been replaced by the (then) new breeze theme for GTK.

On first login, the GTK themes are set to "BreezyGTK" in 42.1 (without
updates).

The breeze-gtk package in Leap 42.1 Update contains a patch to switch the user
config from "BreezyGTK" to "Breeze", but this is missing in Factory.
(the upstream update script doesn't change "BreezyGTK", as that was never
officially part of KDE, it only changes "oxygen-gtk" and "Orion" to "Breeze")

And the update script is only run on login, so if you install Leap 42.1, login,
and upgrade to Tumbleweed, the user config will still try to use "BreezyGTK"
which doesn't exist.

If you would first install all updates in 42.1, logout/login, and then upgrade
to Tumbleweed, it should work.

On a fresh Tumbleweed installation it works as well, because then "Breeze" is
installed straight away which sets the GTK themes to "Breeze" on first login.

Likewise it would work when upgrading from a KDE4 installation (e.g. 13.2), as
then the GTK themes were set to "oxygen-gtk" by default, which will be switched
to "Breeze".

I think we should add that patch to Factory too.

This probably is also a problem when upgrading older Tumbleweed installations.
And/or upstream it, as it may be a good idea to replace "BreezyGTK" in general.

FTR, this should also affect other GTK applications then, and also upgrades
from 42.1 to 42.2, which actually has been mentioned here already:
http://lists.opensuse.org/opensuse-kde/2016-08/msg00010.html