"switches windows of current application" is broken for macbook keyboard

I have a macbook air 6,2 (2013) with a standard macbook keyboard.
The <alt><key-above-tab> combination for switching among windows in the current application does nothing.

There is a seperate issue with the keymap for that particular key: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1245081

But when I remap the key to properly display the "`" character (using the command 'xmodmap -e "keycode 94 = grave asciitilde"' in the Startup Applications), nothing is fixed.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: unity 7.1.2+13.10.20131014.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.11.0-12.19-generic 3.11.3
Uname: Linux 3.11.0-12-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.12.5-0ubuntu2.1
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
Date: Mon Oct 28 10:07:48 2013
InstallationDate: Installed on 2013-10-25 (2 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64+mac (20131016.1)
MarkForUpload: True
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)