The add-ons seems to work fine for most of my users but there are several reports since the release of version 3.1 that the settings UI is broken and no options can be set. I still get reports with the current version 4.0.1. In version 3.1 I changed the settings UI to an about:-page (about:newtaboverride), so there could be the culprit. There were no such reports in versions before 3.1.
My biggest problem is: I can’t reproduce the issue. I tested it on macOS Sierra and on Windows 10, with Firefox Stable and with Firefox Nightly, in my productive Firefox profiles and with new profiles. I really have no idea what the problem could be. But I want to fix it…
Here you can see a screenshot of the broken settings UI (from the latest error report).
The only way I can “reproduce” the bug is if I navigate to a data: which contains the content of view-source:about:newtaboverride.
Do understainf d this correctly that you have a “dead” about: html page which you script and style with SDK content scripts? It seems those content scripts fail to ally for some reason.
I use about: pages for all my addon interfaces as well because the URL is so clean.
I reproduced it. It works fine if I open in normal window, but if you open a private window, then go to the page you get this broken-ness - Imgur: The magic of the Internet
Also if your history is set to “never remember” it also reproduces the issue: