I have a crapload of addons, some of which may not be compatible with v3. I’d rather wait a couple of months to give the authors time to update them before upgrading to the new version, but I’m not sure if the newer, better, shiner auto-updating Firefox will let me block the updates it’s so excited about looking for. Is there a way to do that?
Tools > Options > Advanced > Update
Change it from “Automatically download and install the update” to “Ask me what I want to do”.