Awesome addon! One suggestion: swapping the labels of "Blacklist" and "Whitelist", since they're currently contrary to how they're typically used. Normally, things that are whitelisted means that nothing is applied or done to them, which is basically what's happening to entries added to the current "blacklist", however.

Great addon otherwise. The notification pop-up is highly useful, as it can be confusing why a website didn't function like expected. For example, using Google search-by-image-URL, instead of searching, the image instead opens in a new tab. But the pop-up lets you know what happened, and I was then able to whitelist Google Image search (same issue with Google Translate, Archive.org, Archive.is).