Grey border around pavucontrol

[Rovanion]

This bug is best illustrated with an image: [1].

As you can see above there is a grey border around the actual contents of the application. With the adawaita theme it looks quite out of place. This might however be considered a question of taste, but over at askubuntu.com [4] some considered it a bug.

What I've tried thus far is to modify the contents of .config/gtk-3.0/gtk.css according to the pointers given on a probably unrelated bug on CSD [2].

I've tried to select the area around the contents with gtk-inspector but to no avail. [3]

Neither does applying, as seen above, a style removing margins, padding and borders to the background-class associated with the upper-most gtk element have any effect.

Having no experience at all with gtk development I'm unsure where to go from here.

  [1]: http://i.stack.imgur.com/G5Zpy.png
  [2]: https://github.com/shimmerproject/Numix/issues/206
  [3]: http://i.stack.imgur.com/UmfrN.png
  [4]: http://askubuntu.com/questions/752204/remove-grey-border-around-pavucontrol-in-16-04?noredirect=1#comment1121917_752204

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: pavucontrol 3.0-3build1
Uname: Linux 4.5.0-040500-generic i686
ApportVersion: 2.20-0ubuntu3
Architecture: i386
Date: Thu Mar 31 12:21:01 2016
EcryptfsInUse: Yes
InstallationDate: Installed on 2013-08-07 (966 days ago)
InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release i386 (20130213)
SourcePackage: pavucontrol
UpgradeStatus: Upgraded to xenial on 2016-03-17 (13 days ago)

[Rovanion (rovanion-luckey)]

A patch is available upstream: https://lists.freedesktop.org/archives/pulseaudio-discuss/2016-March/025937.html