I've really only tested this on Gecko-based browsers (honestly, I am developing it just on Firefox 1.5 on Windows XP so far, Mozilla 1.7.12 in WinXP is starting to get a little funny-looking).
I *know* it looks awful on IE. Please try using Firefox, preferably on Windows (with which combination you also won't see this annoying message).
Much of the functionality does work in IE, but a lot of the styles are messed up, and that makes it a little hard to use and see what's going on.