"Legacy" addons could be made compatible with the newer multiprocess design. See: https://developer.mozilla.org/en-US/Add-ons/Working_with_multiprocess_Firefox$

"Legacy" addons could be made compatible with the newer multiprocess design. See: https://developer.mozilla.org/en-US/Add-ons/Working_with_multiprocess_Firefox$revision/993443 https://developer.mozilla.org/en-US/Add-ons/Working_with_mul... Many developers went through the effort only to see support for their addons scrapped altogether a couple months later. Fortunately, that was quick enough for Mozilla to sweep under the "legacy extensions are unfixable and unmaintainable" rug.