Comment 8 for bug 587644

A work around is available - actually, to be more accurate, I was able to assign <Super>s to what I wanted in System-Preferences-Keyboard Shortcuts

For those interested in window transparency, there is a program in the software center called transset-df. Install this, then make a key binding to the command /usr/bin/transset-df -p -t 0.3 to toggle transparency to 30%