WebExtensions are a new way to write Firefox extensions and coming in FF46.
This may be what Norton is waiting on to fix FF toolbar.
http://WebExtensions are a new way to write Firefox extensions
This is speculation on my part but since FF is still changing the game I think this may be the future.
WebExtensions are currently in an experimental alpha state. From Firefox 46, you can publish WebExtensions to Firefox users, just like any other add-on. We're aiming for a first stable release in Firefox 48.
WebExtensions are a new way to write Firefox extensions.
The technology is designed for cross-browser compatibility: to a large extent the API is compatible with the extension API supported by Google Chrome and Opera. Extensions written for these browsers will in most cases run in Firefox with just a few changes. The API is also fully compatible with multiprocess Firefox.
We intend to deprecate XUL and XPCOM-based add-ons, and encourage add-on developers to use the WebExtensions API for new development.
FF 46 is scheduled for release in early April.
Jim 