ImageButton is broken. The url is applied to both the source and the background.
However, I think it’s broken by design as well. We have four components called “Button”: Button, TextButton, TextAndImageButton, ImageButton. With the exception of ImageButton, these are all of type “button”. For some reason ImageButton is of type “input”. It seems to me that it should be “button” rather than input. Button elements are much more styleable AFAIK.
