Feature summary (what you would like to be able to do and where):
If new edits are made to a page while viewing the history, it should be indicated in some form on the history page. One approach would be similar to how Watchlist supports "live updates". The tab title could also be updated to indicate new edits, so that it can be seen while working on something else in another tab.
https://en.wikipedia.org/wiki/User:Enterprisey/live-reload is an existing userscript that provides similar functionality.