Gosh, what year is this? I have to do manual focus management for anything remotely outside the box?
Even if I do, then I have to keep track of everything OUTSIDE my form, because that's what Tab and Shift+Tab would normally focus on after the edge elements. Worse yet, I can't even completely emulate the natural behaviour, because the tab-stops normally include browser UI elements as well.
Is there seriously no way of having the browser think the user pressed Tab?
(It's situations like this that I find extremely frustrating when it comes to web development. I'm trying to make a UI that's as smooth as possible, nicer to use than the average UI, and I end up re- implementing everything, or not even being able to if I wanted. All for something relatively subtle...)