> One question I have as a user - what is an acceptable grace period for coming up with an equivalent replacement when you take an API away? Done correctly, th

> One question I have as a user - what is an acceptable grace period for coming up with an equivalent replacement when you take an API away? Done correctly, the replacement should have already been there for one release before the deprecated method is removed; this is because the downstream developers also need to transition to the new code. Ideally there's some amount of time involved (so no releasing two versions in quick succession without letting people have time to move off the old way). That depends more on the scale of what people have been doing with your old APIs. Note that the deprecated method only has to work; it doesn't need to be performant. That means doing it as a shim on top of the new way is fine (even though it's code that might be thrown away soon). All of this has ~nothing to do with what Mozilla had been doing with Firefox, of course. I'm still waiting for features that existed in XPCOM that are no longer supported.