Used to work, now it doesn't please fix this, I beg.

It's "officially" out tomorrow, Nov 14th, but the final build that will be pushed tomorrow can be downloaded a tad early... hope you can look into this Keith.

https://archive.mozilla.org/pub/firefox/releases/57.0/

Very good news, and thanks. A web browser is like one of the most "swap between monitors" windows I use daily.

Just want to add a few things I've noticed;

So the issue with Firefox 57.0 is that the caption buttons don't pick up the middle click "swap" anymore, as seen here. https://i.imgur.com/3Mmfpt7.png

But if go into the "Customize Firefox" window and add the Title Bar (eww) https://i.imgur.com/ROsmYvc.png

These Caption buttons do work; https://i.imgur.com/tyP3CqG.png

So there seems to be two versions of Firefox's "Title Bar" so to speak, the traditional one if you show the Title Bar, and a different form of on that doesn't work.

Also I'm not sure if this has any effect on the outcome, but in the Customize options I also use Density "Compact".

Works great!!!!!!!!!!!!!