Bewertet mit 4 von 5 Sternen

I did read the FAQ and I do understand your reasons... However I'd like to use Firesizer for recording tutorials/making screenshots for documentation and I really only need to capture the site content in a consistent format (HD) and not the full browser window...
Otherwise simple and great add-on. Thanks.

In that case, you will probably be better served using the built-in Responsive Design mode where you can set the viewport size. It's under Tools / Web Developer, or you can press Ctrl+Shift+M.