Firefox for Linux and macOS use system-specific desktop notifications.
This add-on allows you to disable this integration, and revert to notifications that are implemented using XUL.
Firefox 59 and later: Set the
alerts.useSystemBackend preference to
false (bug 1418287).
MacOS, Firefox 57 and later: install version 0.2 to disable native notifications.
Linux, Firefox 57 and 58: Add-ons cannot disable native notifications. See README, Linux to learn how to disable native notifications. And then disable this add-on.
Firefox 56 and earlier: Install version 0.1 of the add-on.
For more details, see https://github.com/Rob--W/nnnotifier#readme