[ic] [tree] memo toggling

[Brendan Crosser-McGay]

Can someone give me a little insight into how memo and toggle work in
relation to the [tree] tag.

I'm trying to make windows-explorer-like expanding categories with unlimited
amounts of subcategories (limited by system of course).

I know most of the ways of doing this but I know that the toggle parameter
must be the key to making these subcategories work right.  If there is one
variable for each leaf of the tree, I can't figure out how to make tree
distinguish between one leaf and the next.

I don't know where to start with this so if anyone can just give me a little
boost I would be very much appreciative.
-Brendan