It works! It also does not disappear anymore when you scroll down the code block.

Great and really handy. Just one small detail: the extension button doesn't show in the toolbar in FF (just an 'invisible' clickable button), it does in Chrome.

Very handy! ... I would rate 5 stars except the button disappears when I scroll down in a code block. (See image: https://ibb.co/bZVfbn)