User Agent: Mozilla/5.0 (Windows NT 6.1; rv:56.0) Gecko/20100101 Firefox/56.0 Build ID: Gecko/20100101 Steps to reproduce: Open about:preferences throw typing it into the addressbar. Same for about:addons. Actual results: The address bar does not show any suggests for auto-completing about:preferences Same for about:addons. Expected results: Typing about:preferences should be auto completed in the address bar. Same for about:addons. Maybe after typing about: there should be a list of all available about: pages.

Thanks for filing this bug! I'm going to close this bug as a duplicate of bug 462674 since we already have something like this on file, but your input is very valuable :)