In the forums, there is an icon left of each thread - with a star if read and blank if not - or at least I assume that is its function from looking at the code and seeing what you named the image files. 

But when I click on a post and read it, and then click on New Threads to list that page, the thread I just read still has the star on it?

The forums currently use session-based unread status tracking, and for the duration of your session, content posted after your previous visit will be marked as "unread". There's currently no other read status changing setup, although there are two (first the one I suppose you anticipated) that could be added in without too much trouble:

• Session-based with read status changing as content is accessed
• Full database-rooted read status tracking that lasts across sessions

As for where exactly these two features fit on our roadmap will be seen by the end of the month, as soon as we get enough space to have a dev meeting and evaluate the huge list of possibilities that's been piling up.

The first of the two takes two dozen lines of code or so, so I could throw that into the next WWB update if wanted.

Not a bid deal to me.  In part wanted to share my feedback as a user that it did not work as anticipated.  And in part I had just noticed it and was wondering if it would be a useful tool for me to use so I could track which of the forum posts I have read and which I had not.

From what you shared, could you say what a "session" is.  Given that I keep my computer on all the time, have checked off some long period of time (months) when I logged in, and leave the forums open as I am constantly trying to move through my development, I suppose my session only ends when I restart a browser? which only happens when I am trying to provide detailed feedback on bugs at this point.

Ideally?  It would be a useful function for me if it indicated to me if I had read/viewed the latest post per thread - indicated on a per thread basis - and changed as soon as I viewed that post.  Ie, if there is a new post that I have not read, I would love to have an indicator next to the name of that thread.  But that is me and my use.

Session starts when you open your browser on the site, and ends when you close your browser.

Read status controls are standard features that we should have built-in beyond what's already there. Noted for future development.