ok, I will mention one more idea threaded and nested view mix: when I choose some threaded post, I suddenly lose a broad view of where it was in msg-tree.
1) I propose to expand those msgs, whitch are the nodes of the branche I am interested in, and leave others just headers for orientation. 2) now you see just the current parent post expanded, and it would be nice to see several levels of children expanded (one more get variable).
ok, for the 1-rst part to expand msg's some backtracking is needed. but probably, when rendering, the tree is first made-up in some array. so just make a flag for each elem - show_full, and check them from current msg/node up to the root of topic via *parent*s
and for part 2 just count relative_depth variable and if it is less than leves, also check show_full = true;
it is possible to accomplish similar things with js ( style = "display:none|block" + traverse_tree script ) for example http://tadas.hn.org/~jurgis/listing/index.php?dir=/edutech try clicking on menu on right (sorry, I'm lazy to translate)
ps.: some different angle idea about thread/topic http://moodle.org/mod/forum/discuss.php?d=10019#53761