jwz‘s message threading implementation page is very cool. It’d be interesting to see the database method that “Netscape Confusicator 4.0” used. Here’s an interesting observation jwz made (yep, it’s still a problem in Mozilla):
The 4.0 UI presented threading as a kind of sorting, which is just not the case. Threading is the act of presenting parent/child relationships, whereas sorting is the act of ordering siblings.
That is, 4.0 gives you these choices: “Sort by Date; Sort by Subject; Sort by message number; or Thread.” Where they assume that “Thread” implies “Sort by Date.” So that means that there’s no way to see a threaded set of messages that are sorted by message number, or by sender, etc.
There should be options for how to sort the messages; and then, orthogonal to that should be the boolean option of whether the messages should be threaded.