A button that displays config pages, you can also access and bookmark

http://about:about

for the same result

about:about
about:addons
about:buildconfig
about:cache
about:checkerboard
about:config
about:crashes
about:credits
about:debugging
about:devtools
about:downloads
about:home
about:library
about:license
about:logo
about:memory
about:mozilla
about:networking
about:newtab
about:performance
about:plugins
about:policies
about:preferences
about:privatebrowsing
about:profiles
about:restartrequired
about:rights
about:robots
about:serviceworkers
about:studies
about:support
about:sync-log
about:telemetry
about:url-classifier
about:webrtc
about:welcome

Sad that yet another nice addon can't function properly because of Mozilla.
I think it would be nice if you change the greyed out menu entries to put the url on the clipboard.