User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:6.0a1) Gecko/20110429 Firefox/6.0a1 Build Identifier: Mozilla/5.0 (Windows NT 5.1; rv:6.0a1) Gecko/20110428 Firefox/6.0a1 See screen shot. Reproducible: Always Steps to Reproduce: 1. Activate an app tab 2. Put focus in the url bar 3. Shift-Tab to move the focus backwards, until you reach the app tab Actual Results: Focus rectangle bigger than the app tab itself. Expected Results: Focus rectangle fitting inside of app tab.

Kai, can you check which build on trunk is the first one which shows this behavior?

Certainly, I will get back to you soon.

OK, I tried a lot of nightlies through mozregression, and even the one yesterday didn't show the problem. Then I applied a persona, http://www.getpersonas.com/en-US/persona/398309, and then the problem appeared. Need to do that bisect again though and put that persona on everytime I try a nightly, since I didn't do that on the first run...

I tried with the "Nightly and Aurora" persona (http://www.getpersonas.com/en-US/persona/398309) on all builds and this is the result of the bisection. Last good nightly: 2010-10-05 First bad nightly: 2010-10-06 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=10a6b2c105ae&tochange=dee1e01fd8ed The most probable culprit after doing my layman analysis is bug 597353 (Ensure pinned tabs have the same height and alignment as normal tabs).

Thanks Kai. Yes, it's the only bug in this list of changesets which would make sense to have caused this regression. I tried it on my own in a Windows VM but I don't see a focus rect at all for app tabs. That's weird.

User Agent: Mozilla/5.0 (Windows NT 5.1; rv:50.0) Gecko/20100101 Firefox/50.0 I have tested this issue on Windows XP x32 and Windows 10 x64 with the latest Firefox release (47.0) and the latest Nightly (50.0a1-20160704030211) and could not reproduce it. After installing the theme specified in comment 4 and following the STR from the description, when shift-tabbing from an app tab to another, the focus rectangle doesn't exceed the app tab. Is this still reproducible on your end? If yes, can you please retest this using the latest Firefox release and the latest Nightly build (https://nightly.mozilla.org/) and report back the results?

Marking this as Resolved - Incomplete due to the lack of response from the reporter. If anyone can still reproduce it on latest versions, feel free to reopen the issue and provide more information.