Bug#824891: gtk+3.0: latest version breaks external themes

[Ximin Luo]

Source: gtk+3.0
Version: 3.20.4-1
Severity: important
Tags: upstream

Dear Maintainer,

The version currently in sid breaks external themes including those included in
gtk3-engines-breeze and gtk3-engines xfce. Downgrading back to 3.18.9-1 [1]
solves the problem.

I've not investigated the full extent of this but attached are two screenshots
of some of the issues. It basically makes large sections of the UI completely
unusable.

gedit: if using a dark theme (such as Breeze-Dark) the main text pane background
becomes transparent, but the foreground text color remains white.

pavucontrol and others: borders+padding around menu buttons are not shown, and
widget elements like sliders and checkboxes are not shown either.

I'm trying to go through the git changelog but it's massive and will take me
quite a lot of time. Please forward this as approriate.

X

[1] http://snapshot.debian.org/package/gtk%2B3.0/3.18.9-1/

-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'stable'), (300, 'unstable'), (200, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.5.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.utf8, LC_CTYPE=en_GB.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
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