User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0 Build ID: 20170902220453 Steps to reproduce: 1. Open FF. 2. Screenshots icon is missing from the URL bar. 3. Open hamburger menu -> Customize to add it. Actual results: Screenshots icon is not available in the selection. Expected results: Screenshots icon should be available in the selection so I could add it to the URL bar.

See https://www.mozilla.org/en-US/firefox/55.0/releasenotes/ > Make screenshots of webpages, and save them locally or upload them to the cloud. This feature will undergo A/B testing and will not be visible for some users. It's coming this Tuesday as per https://mail.mozilla.org/pipermail/gofaster/2017-August/000767.html

The screenshots button was moved to page action menu in location bar instead toolbutton of nav bar. see Bug 1366041