I am currently using this on Firefox Nightly Android. I love it but it doesn't work properly on large pages as the dialogue box for download never appears and selection download doesn't work as well.
The dialogue box should open in a new empty view. So should not interfere with the page you are viewing. The selection for capturing a selected region was badly visible on "dark theme" websites. A fix for this is on its way.
BUT again: This is not the right place for this. In future, PLEASE use the provided GitHub link to create an issue. This also allows proper discussion.
