With dual displays unity launcher favours windows on its own display

On a dual display system (Quantal alpha up to date) if an application has multiple windows open on different displays then using the launcher icon to return to the app goes to the window on the display the launcher is on, even if the focus was previously on the other display.

To reproduce, on a dual display system with the launcher on the right hand display open two firefox windows and place one on each display.
Open a Nautilus window and place it partially over the firefox window in the left hand display.
Click on the Firefox window in the left hand display then on the Nautilus window.
Click on the Firefox launcher.

What should happen: focus should return to the Firefox window in the left hand display
What happens: focus goes to the Firefox window in the right hand display.

If the launcher is moved to the left hand display then in the equivalent situation focus will return to the firefox window in the left hand display.

The symptom does not appear to be specific to the application, reversing the role of nautilus and firefox in the above scenario results in focus returning to the wrong nautilus window.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: unity 6.2.0-0ubuntu4
ProcVersionSignature: Ubuntu 3.5.0-13.14-generic 3.5.3
Uname: Linux 3.5.0-13-generic i686
ApportVersion: 2.5.1-0ubuntu3
Architecture: i386
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: Thu Aug 30 13:39:35 2012
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha i386 (20120730.1)
ProcEnviron:
 LANGUAGE=en_GB:en
 TERM=xterm
 PATH=(custom, user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)