Feature summary (what you would like to be able to do and where):

At present, if &useskin= is used in page’s URL, MediaWiki shows a single page in that skin.

Example: https://teflpedia.com/index.php?title=English&useskin=vector

However, all internal links from that page don’t include &useskin= and so clicking on any of them takes you back to the default skin (for logged-out users) or the one specified in preferences (for logged-in users).

Propose that &useskin= should be added to any internal links within the page, so that the user can continue to test the skin on different pages until they close the browser tab. There needs to be an exception made for when an alternative value for &useskin= is specified in the URL.

A second step would be to have a box for logged-in users saying "do you want to keep this skin as your preferred skin?" OK / cancel. Click OK and the user's preferences are changed. But I think the above needs to come first, then the second bit after.