display issues with gtk3-3.20 upgrade

[chakravala]

When upgrading to gtk3 version 3.20, the Albatross theme no longer displays properly.

The release notes state that theming has been fundamentally reworked:
https://git.gnome.org/browse/gtk+/plain/README.in?id=3.20.0

• The way theming works in GTK+ has been reworked fundamentally, to implement many more CSS features and make themes more expressive. As a result, custom CSS that is shipped with applications and third-party themes will need adjustments. Widgets now use element names much more than style classes; type names are no longer used in style matching. Every widget now documents the element names it has and the style classes it uses. The GTK+ inspector can also help with finding this information.

[Telkhine]

I'm also having this unfortunate issue. I'm not positive why the rework was done on a minor gtk3 update, but there doesn't seem to be any changing of things already done.

[JotaRandom]

GTK 3.20 includes a major rewrite of the theming code and broke ALL existing GTK3 themes.

Since Albatross's generally unmaintained these days, we need a volunteer to update Albatross to provide at least super-minimal GTK 3.20 support. Some people still do use Albatross. (It's packaged in a few Linux distros).

[James-E-A]

I absolutely love the Albatross theme! It is the best dark GTK theme I have used, the only one that does not either have ugly pale blues leeching through in various places or broken text fields by dark backgrounds.

However with these changes pavucontrol has visually broken 😢