I think I understood you just fine. What I am trying to get across is that the bookmarking feature is much more useful, because it covers more use cases.
1) Feature 1 - "Mark as Unread" for message X and further on.
This is the feature I suggested. It is very easy to implement and will cover most needed cases.
This covers a single, limited use case. This use case can be summed up with the following description:
User is reading a thread. She opens a new message/page of messages. She stops reading the message/page without finishing it and wishes to continue later from said message (or a specific message on said page). She marks said message as unread. Later she opens the thread and is presented with all messages in thread starting from the said message.This should indeed be fairly easy to implement, since the system seems to store user's progress in a thread with a pointer/link to a single message. The feature only needs to alter this link.
How useful would this feature be? You have requested it and believe that it covers most user needs in the forums, while I have never seen a need for a feature as limited as this one. I can just as well push the left arrow to open the previous page in the thread. As we can see, it is a very personal question. To me this feature only means extra clutter in the user interface. If someone really likes it, it is of course no problem to me.
2) Feature 2 - "Mark as Unread" for message X, X+3, Y and so on (at the same thread).
This would be an improvement of the first feature. It covers a more complex use case:
In addition to the use case description above, the user can set any number of messages in the thread as unread. Upon opening the thread, the user is presented with messages set as unread by herself, the messages that were left unread during previous session, and all new messages that have been posted to the thread.This is functionality that I would find some use for myself. I could for example mark one or two key posts in a thread as unread, so if need be I could get a good recap of the thread content when getting back. When opening the thread again, the marked messages would again turn read. This is not very user friendly, so it could be a good idea to implement a different category for the user-marked unread messages. I think the usability may still too limited to make this feature interesting. Furthermore, if my understanding of the current system is correct, pretty significant changes would be required to the way threads are handled to implement this feature. There are also some memory implications.
I don't think this was even a feature anyone really suggested, but rather this problem area popped into the discussion when I was explaining the assumed limitations of the current forum system and how it affects your suggestion.
3) Feature 3 - "bookmarking messages"
The difference from "feature-2" is that it will bundle different messages from different threads to a single location.
Again, this is even much more complex to implement, and here the value (benefit) from the previous feature (the 2nd one) is realy low.
The bookmarking feature for forums allows for a much improved user experience. In addition to the use cases discussed above (where bookmarked messages are automatically a different category than read/unread messages), you can for example implement:
- a separate user interface for the bookmarks (you see what you bookmarked and why)
- lists of threads/messages with most bookmarks (a "read this" recommendation system)
This is again more complicated to implement than a feature where you just move the read/unread line. However, it provides new ways to effectively use the forums.
I should also add that the bookmarking feature does not rule out your suggestion in any way. It could still be implemented. My point is that I however see no use for it due to its limitations. The bookmarking feature