Currently, a button element with align='left' or align='right' causes the text contained in the button to be aligned left or right respectively. Firefox always renders the content center-justified. Opera has the same behavior as us. I have not tested in IE6 or IE7.
Created attachment 12162 [details] testcase
(In reply to comment #0) > I have not tested in IE6 or IE7. Like FF, IE6 has centred text on all buttons.
Created attachment 12165 [details] patch
Comment on attachment 12165 [details] patch r=me
Landed in r18528.