I wrote the first version of Firefox extension of Simple Gmail Notes about one and half year ago, and now I am forced to develop a new one using WebExtension technology, because the old jpm addons would be fully disabled after Firefox 57.
That was quite a surprise, because when I started to develop the extension back then, jpm was the most recommended technology for Firefox addon development. And I suffered so much during the development.
Anyway, now the the extension already got some problems with new Firefox (FF 50+), especially with the OAuth. So I am left no choice except starting on this ASAP.