notification-area-applet has white background while gnome-panel has black background

[relgames]

All icons at notification-area-applet have white background.
They should have panel's background.

http://askubuntu.com/questions/171097/ubuntu-12-04-gnome-classic-white-background-for-systray-icons

1) The release of Ubuntu you are using, via 'lsb_release -rd' or System -> About Ubuntu
Description: Ubuntu 12.04 LTS
Release: 12.04

2) The version of the package you are using, via 'apt-cache policy pkgname' or by checking in Software Center
gnome-panel:
  Installed: 1:3.4.1-0ubuntu1.1
  Candidate: 1:3.4.1-0ubuntu1.1
  Version table:
 *** 1:3.4.1-0ubuntu1.1 0
        500 http://nl.archive.ubuntu.com/ubuntu/ precise-updates/universe amd64 Packages
        100 /var/lib/dpkg/status
     1:3.4.1-0ubuntu1 0
        500 http://nl.archive.ubuntu.com/ubuntu/ precise/universe amd64 Packages

3) What you expected to happen
Icons should have black background (from current theme)

4) What happened instead
Icons have white background

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: gnome-panel 1:3.4.1-0ubuntu1.1
ProcVersionSignature: Ubuntu 3.2.0-27.43-generic 3.2.21
Uname: Linux 3.2.0-27-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.0.1-0ubuntu11
Architecture: amd64
Date: Fri Aug 3 11:25:16 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
SourcePackage: gnome-panel
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[relgames (relgames)]

Note: is affect my work machine but doesn't affect home laptop (they both have Nvidia card)

[relgames (relgames)]

Additional details: managed to solved it by switching from Xinerama to Nvidia TwinView