At least, it sort of makes sense to do inside a browser, as you don't need to load in an entire web browser as a library. Also just in general, the long-term p

At least, it sort of makes sense to do inside a browser, as you don't need to load in an entire web browser as a library. Also just in general, the long-term plan for Firefox is to phase out XUL and to replace it with HTML/CSS/JS, so this is not just someone choosing to write their application in web technologies for no reason, but means that they will actually have less maintenance work.