Did you spend a single second to look at the link example I provided?
Seems not because only for subforums there are + signs and not the whole forum.
The whole Idea of this thread is to start thinking of a totaly new way to navigate a forum.
Noone is forcing you to work on it nor use it but it is defenetly worth spending some thoughts about it.
The current forum navigation is custom for us forum users but for users which are new to forums it is not intuitive like using the breadcroumb or find the forum jump at the bottom right.
An explorer like concept is much more custome to 98% of all internet users because they now it from there windows