All browsers support document.all; see [1]. It is true that Opera tried to reverse engineer more of the IE DOM than most others, for example we were the only o

All browsers support document.all; see [1]. It is true that Opera tried to reverse engineer more of the IE DOM than most others, for example we were the only ones to have attachEvent and friends. But in recent years that caused problems with sites that made false equivalences like "has attachEvent -> must be IE" and so non-standard features were being actively removed. It is also true that Opera has been heavily involved in the standards process; both in codifying the legacy and in more forward-looking initiatives to add novel functionality to the platform. For example Hixie was working at Opera when he started work on what became HTML5. Opera's Simon Pieters wrote a spec for CSS quirks mode [2]. We have also been involved in numerous other specs, and in the beginnings of the effort to produce a comprehensive vendor-neutral testsuite for web platform technologies. [1] http://software.hixie.ch/utilities/js/live-dom-viewer/saved/2099 http://software.hixie.ch/utilities/js/live-dom-viewer/saved/... [2] http://quirks.spec.whatwg.org/ http://quirks.spec.whatwg.org/