In pages of Page namespace, it would be useful to have a direct link to the pages in ns0 that transclude the current Page.
Example: I have a page Page:SomeNovel.djvu/42. This page contains the end of Chapter 3 and the beginning of Chapter 4 of SomeNovel, so Page:SomeNovel.djvu/42 is transcluded into SomeNovel/3 and SomeNovel/4.
So on the top of the screen, near the tabs "<", ">", "Page", "Image", "Index", I would like to have 2 similar tabs: "Chapter 3" and "Chapter 4".
In this way, from Page 42 I can go directly to Chapter 3 and check if page 42 looks nice when transcluded there.
This has been implemented on it.source as a gadget, but I think it would be nice to embed this feature in the ProofreadPage extension.
Gadget source code: https://it.wikisource.org/wiki/MediaWiki:Gadget-puntanoqui.js
Example page with 2 links (the two tabs with the open book icon): https://it.wikisource.org/wiki/Pagina:Pensieri_e_giudizi.djvu/31
The gadget calls the API with action=query, list=embeddedin, einamespace=0, and the Page title, to obtain the list of ns0 pages where Page is transcluded, and then for each result just puts a new tab in the #p-namespaces bar.
So this task is about doing the same thing at the ProofreadPage extension level, to make it into a standard feature of ProofreadPage.