Can WebExtensions interact with about: pages now? If not, is there any chance for them to do so in the future? I have just started trying not to use legacy add-ons. Here are a couple things I have hit so far:
I tried the “Dark Mode” extension for giving Firefox a dark theme at night (previously I used Stylish). It looks great, but whenever I switch a page to Reader mode, I am blasted with a fully white background behind black text. I think this is because Reader mode uses an about: url and Dark Mode can’t apply its theme to about: urls.
I am trying Vimium-FF as a replacement for VimFx. Whenever I look at a Reader mode page, or about:addons, about:debugging, etc. or addons.mozilla.org, none of the keybindings work and I have to use ctrl+Page Down to get to another page so the key bindings work again.