In fact, I see this so much here's a blog post about it: http://jarofgreen.co.uk/2012/06/fixed-page-elements-must-die...
It's one of the reasons why Prototype.js was created, and one of the reasons that people use CoffeeScript, don't you think?
Thing is, that CoffeeScript solves the most common pain though (the *.prototype syntax), and the chasm between that and interfaces, singletons, private members, etc., might be too big for the standard use case.
Also, swipe doesn't seem to work on Chromium 17/Fedora. Otherwise, great work!
Then I looked at the DOM HELPERS and said "yeah I've had to build that from scratch" for every single one.
Very good copy, too. This looks good.
Very impressed. I started listing a few I especially liked but then ended up listing the whole lot.