Last night, I noticed that the usual Dock icon for Firefox developer Edition had changed from Blue Fox to what looked like the App Store brush/pencil triangle. I restarted but it persisted. Removed the application and re-downloaded and re-installed, but same issue. I then noticed that all the Tools -> Web Developer tools had gone from the menu. Likewise, doing Firefox -> About inserted 'about:preferences' in the search bar, but nothing else happened. Tried launching the settings from the right side hamburger menu, again nothing happened. Read around a bit, and deleted one of two profiles from ~/Library/ApplicationSupport/..., then tried re-install and restart the Developer Edition, but that complained that a profile was missing. Restored the profile I deleted, but same problem as before. I'm stumped. Can anyone help with this one please? I'm on Mac, latest version of Mojave. Thanks