shift-command-J
Go to about:config, change xpinstall.signatures.required to false.
about:devtools-toolbox?id=drsjb80%40gmail.com&type=extension
* https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Anatomy\_of\_a\_WebExtension
* https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API
* https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json
* https://developer.thunderbird.net/add-ons/mailextensions/supported-manifest-keys
* https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/version/format
* https://developer.chrome.com/docs/extensions/mv2/manifest/version/
* https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/storage
* https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/user\_interface/Options\_pages
* https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/menus/ContextType
* Can't preview on tools menu as there isn't a hover or mouse enter event.
* https://developer.thunderbird.net/add-ons/mailextensions
* https://addons.thunderbird.net/en-US/developers/addon/submit/distribution