This page tests the DOM tree events.
These events do not work with traditional event registration.
Safari warning: Uncheck the window and document checkboxes immediately, before doing anything else. Any change to the control panel on the right adds a log entry, which fires DOM modification events that cause more log entries, which causes more DOM modification events, and Safari will go into an eternal loop.
(I was able to solve this problem in Firefox and Opera, but my solution doesn't work in Safari.)