XBL 2.0 was doing well on the standard track and would have made that happen [1], but it died along with all the other technologies whose acronym starts with an

XBL 2.0 was doing well on the standard track and would have made that happen [1], but it died along with all the other technologies whose acronym starts with an X. Flexbox was by the way implemented in Mozilla back then, I used it all the time in XUL, but then that acronym also starts with an X [2]. [1] https://www.w3.org/TR/xbl https://www.w3.org/TR/xbl [2] https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XUL https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XUL