I had it installed, but right before all this trouble happened, Firefox upgraded itself to the latest version (47.0, I believe). I just took a look at my add-ons, and NoSquint is incompatible with the latest Firefox, and has been permanently disabled (the information says it's no longer being maintained).Maybe you could try the NoSquint addon. It's what I got back when I tried a search related to your problem just now.
So I'm investigating other options.
Thank goodness this problem isn't affecting my XP computer. It's driving me nuts on this one (8.1).