Selfoss Notify

Checks and shows unread items count in your Selfoss RSS reader (http://selfoss.aditu.de). Aslo provide simple interface to interact with Selfoss. Add reader URL in settings, you must be authenticated in reader or addon try to authenticate with password manager.
Left-click on widget opens tab with your Selfoss URL, middle-click (or shift+click) - force update, right-click (or ctrl+click) - open items preview.