Firefox v57 (november 2017) will only support WebExtensions. This rework could benefit to Chrome and Opera users that allow them to use Opquast Desktop on their browsers. See [Porting a legacy Firefox extension - Mozilla | MDN](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Porting_a_legacy_Firefox_add-on) and [Extending the developer tools - Mozilla | MDN](https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Extending_the_developer_tools)