This one drove me nuts. Many developers were achieving the same result in firefox 3.6 and earlier using an XUL hack - but in FF4, the ability to do that XUL hack was removed for (valid) security reasons - but without addressing the text-overflow: ellipsis issue for which they'd had an open bug tracker entry for about 5 years. There were many complaints about this months before FF4 was released but they went ahead anyway.