Comment 6 for bug 408765

Twitter, Facebook, and Flickr -- the first three examples I can think of -- don't seem to use any special styling to show that a form submission keeps you on the same page. And however much you need to know that, you don't really need to know it until after you've clicked the button, so I think a spinner after you've clicked the button is quite enough (as long as the spinner is relatively close to the button).