High Contrast mode results in unreadable text and distorted text fields

The greeter has an option for High Contrast mode in its accessibility menu. When I enable it, the result is the opposite of what we might expect:

 - Any text in the top bar becomes either dark grey on darker grey (time, keyboard layout) or light grey on lighter grey (system name).
 - "Log In" buttons become easier to see, but Password fields are distorted. There appears to be some kind of rendering issue here.
 - Menu backgrounds are still light grey (which is strange, because this doesn't happen in the High Contrast theme I know), and disabled menu items are rendered as dark grey on light grey.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: unity-greeter 12.10.3-0ubuntu2
ProcVersionSignature: Ubuntu 3.5.0-15.22-generic 3.5.4
Uname: Linux 3.5.0-15-generic x86_64
ApportVersion: 2.5.2-0ubuntu4
Architecture: amd64
Date: Sat Sep 22 10:43:02 2012
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Beta amd64 (20110906)
SourcePackage: unity-greeter
UpgradeStatus: Upgraded to quantal on 2012-08-26 (26 days ago)