After a bit more work on interactivity code, I began doing some more testing across different browsers, and hit what looks like a major Safari bug -- a show-stopper for the GUI, really. If a <select> element is included in a resizable container, then you cannot select any of the options in Safari (tested on 3.1 on Windows and OSX). I've posted a report in the JQuery UI bugtracker and on their mailing list, so we'll see if anyone can suggest a workaround; meanwhile, I might have to disable resizing on Safari to get around this. That would be a real shame.