Is Avant Window Navigator Available For Ubuntu 14.04?
If you check launchpad you will see that AWN Testing has support for 13.10, 13.04 and 12.04. So no 14.04.
You have 2 options:
wait for them to update to 14.04.
install the 13.10 or 12.04 versions of AWN. You can do this by opening "software&updates" and editing the source list for AWN. If you change the distribution name you can install it from the older repositories. Mind you: it is possible. If it is wise I'll let you decide (mixing distributions can make a mess of your system).