This is an interesting idea, but not in the next version. I'm working on the internals right now and don't want to introduce behaviour changes.

Thanks. Do you think you can keep this addon going when XUL gets removed from Firefox?
I'm relying on it now for feeds that Feedly can't seem to keep up with, especially reddit.

Working on it. Brief is my primary feed reader, after all.

That's exactly why I'm removing XUL from Brief as much as possible. Unfortunately, there's some technical debt that has to be dealt with.

One last request for me while you're working on this project.
Could you make the titles wider in Headlines mode.
I changed it on one of my computers but not this one. It is a pain that Firefox doesn't let you install unsigned addons any more. I don't like trust running a dev version as my main browser.

You can do that yourself with a custom style (Options - Options - Customize) like

.headline-container {
  flex-basis: 1200px !important;
}

Thanks. That's handy. :)