From:  jorgev <>
Date:  20 May 2011 06:53:59 Hong Kong Time

Making add-ons compatible with Firefox 5


Firefox 5 was recently merged into beta, and it should be released in
final form within a month or so. Luckily, this fast release cycle
means that upgrading add-ons for Firefox 5 is very easy. The upgrade
documentation can be found in this article:

You'll be happy to see that there are pretty much no breaking changes
for add-on developers. The only bugs that I think worth noting are the
following 2:

Change navigator.language to use Accept-Language instead of the UI
language. This affects you if you're using "navigator.language" to
figure out the browser locale. You should use the
"general.useragent.locale" preference instead.

Nested setTimeout should clamp to 4ms instead of 10ms. If you're using
setTimeout / setInternval to handle precise timings and you're relying
on the default minimum to be rounded to 10ms, this is no longer the

As usual, developers with binary components will need to recompile
with the corresponding SDK. Developers not affected by these bugs
should test Firefox 5 compatibility soon and update their information
on AMO. The beta should become available here soon:

If you run into any compatibility problems with Firefox 5, we really
want to know, so please post or contact us directly.