Mark Threads Unread (vB4)
 

This product undoes thread read marking so the thread will show in New Posts in case you want to come back to it later. Open the Thread Tools menu and click the button at the bottom. Enable/disable is in General Settings.

Improved version now handles both database and cookie methods of marking threads read. The link now shows only for threads younger than the read marking limit.

Bug fixed The improved version had a bug, which I have fixed.

Installation: Import the product file in Product Manager

Reserved

That's cool nerbert, glad you found a way to do it. :)

It should be mentioned that this only works for threads that are newer than the global new/unread cutoff. If your forum shows new threads to your users for seven days, only threads from the last seven days can be marked unread. Or did you find a way around that?

When thread is marked read the threadid, userid and read time are recorded in the data base. This product simply deletes that entry based on threadid and userid.

I haven't followed through all the code but I would assume a year old thread isn't shown in New Posts simply because search.php searches back only so far (the seven days you used for an example). So to show a thread older than seven days you would have to build a special table to store ancient threads marked unread and append that list to the New Posts search. It's doable I suppose but far more work than I want to get into.

That's what I derived from your code ;)

That's not how it works. Search.php has nothing to do with it. The markread table is pruned by a cron job. All threads that are older than the cutoff will be deleted from that table automatically. It would grow enourmously big if that would not be the case, since a value is stored for every thread for every user that reads it.
It's not only for the New Posts search. The unread markings are used all over the place (bolding in showthread, for example). And there are other tables (for read groups, for example).

Your addon does what is possible, and I'm sure many will find it very helpful. It's great you made it. I've looked into the system quite extensively for an addon of mine, and chances are you'll pretty soon hear requests to extend it. I had to explain the limits of the system quite a few times...

Thank you @Nerbert and @Cellarius, I looked at the code for unread markings and received a headache for the undertaking. I really appreciate your discussion on this subject.

Even if it's only able to be marked unread for one day, that'll still do it. I have an online classroom and check the forums every day, sometimes I want to mark a thread unread to come back to in a day or so, not usually longer than that. Sweet, installing now, THANKS. Happy to donate a bit of $ as well...

Hi all,

Where do I find my current "global new/unread cutoff." ?

I am taking a stab at what you are asking. See if this helps:
ACP -> Options -> Settings-> General Settings --> Database Read Marking Limit