Part of screen becomes black when changing dash size

[Alan Morgan]

When I change the size of the dash from full screen to the top left of the screen, most of the area no longer covered by the dash becomes black. This did not occur in the past but has begun to reliably happen. I have attached a video.

It happens when a window is below the dash as well.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: unity 5.12-0ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-24.37-generic 3.2.14
Uname: Linux 3.2.0-24-generic x86_64
ApportVersion: 2.0.1-0ubuntu7
Architecture: amd64
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,unitymtgrabhandles,workarounds,scale,expo,ezoom,unityshell]
Date: Fri May 18 21:42:19 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120423)
ProcEnviron:
 LANGUAGE=en_AU:en
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_AU.UTF-8
 SHELL=/bin/bash
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)