User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Firefox/31.0 (Beta/Release) Build ID: 20140703154127 Steps to reproduce: First I think you need a non-English OS to make the font name(s) non-English. In my case, I'm using Simp. Chinese Win7 x64. It's easy to reproduce: just change one font setting to a some fonts like "微软雅黑" In about:support, it will show as mojibake like: font.name.sans-serif.zh-CN 微软éé» In about:config page, this setting is shown as normal. In extension part of about:support page, the string could be Chinese or Japanese without any problem.

#1 Regression window(m-i) Good: http://hg.mozilla.org/integration/mozilla-inbound/rev/dab1d80a04f4 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:18.0) Gecko/18.0 Firefox/18.0 ID:20120918124356 Bad:(empty): http://hg.mozilla.org/integration/mozilla-inbound/rev/35b2c35d3243 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:18.0) Gecko/18.0 Firefox/18.0 ID:20120918140057 Pushlog: http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=dab1d80a04f4&tochange=35b2c35d3243 #2 Regression window(m-i) Bad:(empty): http://hg.mozilla.org/integration/mozilla-inbound/rev/5f3887536eef Mozilla/5.0 (Windows NT 6.1; WOW64; rv:18.0) Gecko/18.0 Firefox/18.0 ID:20120918145357 Bad:(moji bake): http://hg.mozilla.org/integration/mozilla-inbound/rev/be731f9147dc Mozilla/5.0 (Windows NT 6.1; WOW64; rv:18.0) Gecko/18.0 Firefox/18.0 ID:20120918155756 Pushlog: http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=5f3887536eef&tochange=be731f9147dc Regressed by: Bug 554174

OR bug 789674

Not tracking. Has been in Firefox for a while and we won't block the release for this.

I'm not sure why qawanted was added to this bug since this bug has been confirmed and has a regression window. Benjamin, please ensure you always provide details when setting qawanted. We're not great mind readers.

TroubleShoot.jsm uses a getPref helper to retrieve strings: http://hg.mozilla.org/mozilla-central/annotate/668ade60cde9/toolkit/modules/Troubleshoot.jsm#l214 It uses getCharPref(name). The old about:support (prior to bug 789674) used a getPrefValue helper: https://hg.mozilla.org/mozilla-central/rev/83925e071235#l1.656 It uses getComplexValue(aName, Ci.nsISupportsString), which is better. So we should just fix Troubleshoot.jsm to use getComplexValue. (At the same time, we should eliminate the two copies of the "getPref" helper in Troubleshoot.jsm, per bug 804430 comment 18.)

Fixed the Troubleshoot.jsm module: - use getComplexValue to get the Unicode string. getCharPref returns UTF-8 encoded value, would need to be decoded first before usable - refactored the modifiedPreferences and lockedPreferences methods to remove code duplication - added a new test to browser_Troubleshoot.js to test proper Unicode handling

Comment on attachment 8608058 [details] [diff] [review] Fixed Unicode values of prefs in about:support Review of attachment 8608058 [details] [diff] [review]: ----------------------------------------------------------------- Very nice, thanks! I verified it locally and it works as advertised. https://hg.mozilla.org/integration/fx-team/rev/bfe02e08726e

Thanks Drew! What do I need to do next? Push to try? Set checkin-needed?

Jarda, sorry for not explaining. It's already checked in. I pushed your patch directly to our fx-team repo, which is where we do Firefox front-end development and which is what the link in comment 7 points to. Then your patch was merged to mozilla-central, as noted in comment 9, which is the repo that Firefox Nightly is built from. I just tested in the latest Nightly, and it looks like your fix didn't make it in time, so it should be in the next Nightly.

Thank you for an explanation Drew. The fix is right there today, in the 2015-05-22 Nightly.