This sounds great, I will try.
Is it somehow possible to restrict the internet access of a single extension?
For example I have an add-http-header extension that has no reason to create connection to an outside server.
Not sure if this answers your specific question, but you can limit the sites that an extension can run on. I recently discovered that Chrome offers this feature (right click the extension icon and select Manage Extension to access), and it saved me from having to build a site whitelist feature for my extension. [1] It already has a blacklist feature, and I was going to build a whitelist feature due to user requests. Then I discovered that this functionality is built into all Chrome extensions.
Unfortunately it doesn’t seem to exist on Firefox.
If it can modify the DOM or even display its own HTML-based UI, that might be hard because it can embed an external image, and the loading of that image would contact an external website.
Unfortunately it doesn’t seem to exist on Firefox.
1: https://chrome.google.com/webstore/detail/beeline-reader/ifj...