Firefox frequently installs updates to my add ons automatically. That's fine, but every time it does one of these updates, it opens a URL in a new tab. The URL is apparently determined by the add on developer. Often three or more of these extension update tabs open when I start firefox. It's a right pain, and I want to disable the feature entirely. Does anyone know how I might do that? Thanks.
It isn't a Firefox feature but rather something that extensions do themselves. Which means that there is no generic way to disable it, you have to do it for each extension individually. For example, NoScript lets you disable this notification. If some other extension doesn't then you will have to ask the extension author to add that option.
And: yes, opening a page after update without a good reason to do that isn't nice. And there have been debates on that topic (UI-wise and policy-wise). Unfortunately, no solution so far...