Dropdown boxes in firefox stop working after using HUD

[Colin Law]

Using Unity-2d on up to date Quantal with firefox 15.0~b2+build1-0ubuntu1 (though I also see this on 12.04 with firefox 14.0.1).
To replicate
Open firefox.
Open the HUD and select a firefox bookmark.
Wait for that to load then go to a page that has dropdown select boxes. These fail to work.

I do not see the problem in Unity-3D (on Quantal or 12.04).

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: unity-2d 5.12.0-0ubuntu3
ProcVersionSignature: Ubuntu 3.5.0-8.8-generic 3.5.0
Uname: Linux 3.5.0-8-generic i686
ApportVersion: 2.4-0ubuntu6
Architecture: i386
Date: Wed Aug 8 15:50:05 2012
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha i386 (20120730.1)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_GB:en
 TERM=xterm
 PATH=(custom, user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: unity-2d
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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

[jhfhlkjlj (fdsuufijjejejejej-deactivatedaccount)]

Very reproducible. I haven't used Unity 3D in a while because of bug 966744 but I recall having this issue in 3D as well.