STR: 0. set requisite prefs, open browser toolbox 1. Inspect a <menu> in the browser's <menubar> ER: see CSS rules from chrome://global/skin/menu.css AR: No CSS rules from chrome://global/skin/menu.css These rules also don't show up in the style editor. Don't know if that can be fixed in one fell swoop or not.

Seeing this as well when trying to debug style sheets for dev tools itself: Inspect element that has styles applied to it from chrome://browser/skin/devtools/webaudioeditor.css, clicking on 'webaudioeditor.css' in Rules pane just goes to Style Editor, where that file isn't listed.

This WFM now, although links to the style editor are still broken.