Tipsy

(a local fork of tipsy code) is in core, and more technically documented at ResourceLoader/Default_modules. It has been deprecated since MediaWiki 1.28, although as of early 2021, some extensions still load it, such as MultimediaViewer, Wikibase, and UniversalLanguageSelector, and it's used in some on-wiki gadgets as well.

The default code is given Agora appearance and behavior (as specified in mockups like https://trello.com/c/vr0Oai8G) via [?these additional components?].

See also, Open bugs list