As for the 'Show styles' button you can easily see the elements on a page which have the 'Class' or 'Style' property set. It would be convenient to have a similar option called 'Show events'. When active this would show the elements on a page which have an event connected (on change, on leave, on enter). Developers can quickly spot which elements have events on them.
Great idea. That will certainly make it easier to comprehend the behaviour of the page.