One of my users has asked about the possibility of having an option for nested threading, where a post is located below the post it is a reply to, and is indented. The best example I can think of is the IMDB boards and how their threading works when set to the "Nest" option.
Is this a possibility with MyBB?
That isn't Nested Threaded, thats Nested Flat. In Threaded mode, you only see a single post at a time. Flat is also known as Linear.
That said, I'm sure someone could do this modification, however I wont be taking my time since I don't like that particular view. Have him try the normal Threaded mode (User CP -> Edit Options -> Thread View Mode) and see if he likes it. There are some forums I like it for, and some I don't. This is one that I don't.
there's a lot of misconception about the terminology with respect to "flat" thread views vs "hierarchical" thread views of discussion forum activity. Most systems are a hybrid between the two. MyBB's "threaded" view shows the post headers within a particular "thread" in a hierarchical fashion, but not the posts within a thread themselves. The hierarchical view ( the "threaded" option) only provides links to individual posts.
I modified myBB to show a posts in hierarchical fashion. To do so requires rewriting the post display "loop" (in showthread.php) to build a tree representation of parent / child posts in a php associative array, and then parse through that and calculate and pass an indent value to the html ( via the post templates ) dependent on a posts position within the parent / child hierarchy. (i.e. you have to recursively parse the tree structure).
I have found discussion forum developers (not only myBB) generally hold that one view is more advantageous than the other, and forsake flexibility for their particular belief.