The language is official. https://mozilla.github.io/firefox-browser-architecture/text/0005-problems-with-xbl.html https://mozilla.github.io/firefox-browser-arc

The language is official. https://mozilla.github.io/firefox-browser-architecture/text/0005-problems-with-xbl.html https://mozilla.github.io/firefox-browser-architecture/text/... says: > XBL is a proprietary technology developed by Mozilla. We are solely responsible for the maintenance and improvement of XBL. Any time spent on doing this doesn’t contribute to the evolution of the Web so effectively we don’t spend anytime improving XBL except for plugging serious holes. What they mean is they 'own' it, the good, the tedious and the bad parts.