Re: release browser-related packages to stable?
I haven't looked for the official discussion, but extensions have been
updated in stable (to a new upstream version if necessary) when a
browser update would otherwise break them: see e.g. #744730.
Has there already been any further discussion about the solution for Xul
extensions packaged in Debian?
Also, clients for interacting with a single online service (eg. ttyter,
#721921) have been updated in stable when that service changes its API.
Those cases have in common that there is a clearly-defined "right"
version: a browser and its extensions are on the same machine so can be
tied together by the normal dependency system, and a one-service client
needs to match its only server. This isn't the case for a server
intended for public (i.e. with non-Debian clients) use.