Panel has odd spacing, colour artefacts with Adwaita theme

The GNOME Panel, when used as the GNOME Classic session type, does not space out icons correctly and displays an artefact of some sort at the edge of the notification area (this can be seen in the attached screenshot). This screenshot shows the Adwaita theme being used, with a semi-transparent white background for the top panel; the launcher and system tray icons are larger than they should be, with one icon obviously too big. The volume and network applets are too widely spaced out, there being no obvious reason for the blank space between the system tray and the volume control, and between that and the network icon.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: gnome-panel 1:3.2.0-0ubuntu1
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 1.23-0ubuntu3
Architecture: amd64
Date: Tue Oct 25 17:24:38 2011
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Beta amd64 (20110920.5)
ProcEnviron:
 LANGUAGE=en_GB:en
 PATH=(custom, user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-panel
UpgradeStatus: No upgrade log present (probably fresh install)