Taking screenshots from the Firefox "chrome" context

[tombh]

So I'm finally getting round to exploring my rewrite of Browsh and one of the first things I'm looking to improve is to also render parts of Firefox's UI, like the permissions popups, URL history suggestions, extensions icons etc. For that I will need to be able to take efficiently get screenshots of the whole browser, not just the content. I've been playing around with some code and have almost got there, but there's an error I can't figure out. So I've posted to a few places to see if anybody has any ideas:

• https://www.reddit.com/r/selenium/comments/1lurx6x/taking_screenshots_from_firefox_chrome_context
• Taking screenshots from the "chrome" context mozilla/geckodriver#2229
• https://support.mozilla.org/en-US/questions/1521639
• https://www.reddit.com/r/firefox/comments/1luse1f/taking_screenshots_from_the_chrome_context
• https://discourse.mozilla.org/t/taking-screenshots-from-the-chrome-context/144610

Fingers crossed somebody has some ideas 🤞