Sorry, Tomaso, dealing with Pale Moon is so far on the back-burner that it's cold. No decisions yet, one way or another.
An update on the status of things, in no particular order:
1) Trying to write software whilst lightheaded is not fun, nor very effective. Sorry, getting sick is really slowing me down. (I know exactly who I got it from, and they're still sick too)
2) I read some recent postings by Giorgio Maone on his blog for NoScript
, and apparently you can get some "legacy" extensions working under Firefox 58 if you install the developer version and set extensions.legacy.enabled=true in about:config. Emphasis on "some", as Flagfox would not be one of them. The URL bar has apparently changed enough to confuse it. Giorgio is in a similar boat to me, by the way; single developer project, and he planned to release ahead of the Firefox 57 release date, but has still been unable to finish.
3) At the beginning of the year I made sure to check that all of the WebExtension APIs that were going to be needed actually existed. That said, the docs apparently leave out some rather crucial stuff, and some stuff is only shown on one page whilst not on another. (Mozilla's docs site, MDN, desperately needs a redesign; I'll file a bug or something when this is all over, because using the site has been painful) Long story short, sadly, expect some idiocy and ugliness in Flagfox 6.0 that will be due to arbitrary limitations imposed by Mozilla, rather than just me sucking at CSS. I might be able to hack around one, or not; don't know for sure yet.
4) Apparently, Mozilla ditched the bookmarks toolbar icon by default in Firefox 57. They're fucking insane. My mother asked me if Firefox Quantum was the thing I told her I was fighting with, 'cause she hated it. Also, looks like they usurp whatever homepage you have set? Not sure; she was dumped into a new new-tab page that was very much unwanted. Either way, the Firefox 57 user update experience has failed the standard non-techie mother test rather spectacularly, though it didn't take me long to fiddle with it to get it to her liking. The level of clusterfuck here is depressing.
I should probably post this on the blog instead of here, but meh.