I would like the title of my site to change, according to whether or not there are new replies on the current page that I have not read.
So for example, if I have my browser up, I wouldn’t need to be viewing the discourse website to see if a new reply was posted. Instead I would be able to tell by the title (which displays on the tab), if there are new messages to read.
Does discourse already have this feature?
There is a user preference to:
Show incoming message notifications on favicon (experimental)
Awesome thanks. I will try it out.
Granted, I haven’t had any success with that working anywhere else except Meta 
Never actually used it myself either…
Just discovered it works on another Discourse instance, but not the one I’m staff at… weird…
I’ve come close to writing a UserScript to provide this functionality, just haven’t done it yet.
It’ll be due to our customisation.
Ends up it does work on our instance for some… It seems two members (including @TechnoBear now) seem to have it functioning, while I do not. And now @TechnoBear is gloating about it via PM, lol. Something about it only working for those who are “nice” 
Weird… I wonder what browser she is on.
Various. The second member, uses Chrome on Mac and Linux (same as I do for Linux). She was using Firefox on Ubuntu and Chromium on Ubuntu (Chromium worked, Firefox did not).
So it seems flaky for some reason
The Admin Setting for this does say something like "notifications in tab - experimental).
Experimental to me indicates that it might work, might not work, might work only sporadically.
So though I sometimes see it here at meta (like the “unread” count, it seems to be tied with cache-refresh) I haven’t really analyzed it any.
I’m using Firefox, which works for Meta, but not on ours. After another member confirmed it works on our site for him on Chromium, I tested that and it does work for me, but as I prefer Firefox for a number of reasons, that’s not really much help.
(On the other hand, my Firefox spellchecker works just fine on our instance, but not here. Go figure.)
Amending title based on new replies to a topic is not something we do yet
But we will get to it shortly
Works fine on the front page though
Yep, I’m fully aware it is experimental, which is why I’m not stressing about it too much (well until @TechnoBear started to give me a hard time about it – all in good fun, of course)