Component to perform Multiple Select in dropdown for Reactive web

From three simple concepts (Feeds, Channels and Items), a solution is presented to read and write RSS feeds.

Enhanced Dropdown block, with the option to add custom entries by the end-user, as well as search functionality and multiple tags selection. It is a port of the original Dropdown Tags component in OutSystemsUI, with the extended functionalities added. The component was originally developed as part of the OutTracker application (https://www.outsystems.com/forge/component-overview/9951/outtracker) by OutSystems R&D, so credit goes to them. It is extracted as a separate component, to be re-used in cases where the advanced functionalities are needed.