User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:33.0) Gecko/20100101 Firefox/33.0 Build ID: 20141015093046 Steps to reproduce: I've used about:config to set ui.key.menuAccessKeyFocuses to false. This disables the behaviour where the menu pops up while holding alt, because I use alt+scrollwheel to change tabs and the default behaviour breaks that. Actual results: Frequently (every few weeks or so, but unfortunately not with any pattern that I can see), I find that this preference has reverted to its default `true`. I am suspicious that it happens on package updates, but I haven't tried testing that theory. I've added prefs.js into a little git repo in /.mozilla/firefox/<profile>/ to see what changes, and I notice that the "ui.key.menuAccessKeyFocuses" line has disappeared from prefs.js each time the option reverts itself. I've never seen this happen with any other setting. Is there anything else I can do to figure out what's resetting this preference? I can never remember what it's called, which adds annoyance each time I need to fix it in about:config ;) Expected results: The preference should be persisted indefinitely.
It's automatically set when toggling between the autohide and permanently-shown states here: http://mxr.mozilla.org/mozilla-central/source/browser/base/content/browser.js#4432 in order to avoid focus issues when the menubar is permanently shown. I'm not sure what we could do to fix this for you; it'd probably mean resorting to having another pref that overrides this toggling, or something - but that's kind of hacky...
Component: Preferences → Menus
Oh, damn. I do _very occasionally_ need to access the menubar, so it must be reverting whenever I temporarily enable it. Now that I know what's causing it, this extension makes for a much better workaround, as I will no longer have need to toggle the menubar: https://addons.mozilla.org/en-US/firefox/addon/compact-menu-2/ Thanks. Not sure whether to mark the bug as resolved (it's still definitely a bug in my eyes), but I'm happy with the workaround at least.
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