[rjdrafzz] Laying out hierarchical clickable text

I dislike the clickable expandable hierarchical navigation because the items, vertically thin areas of text are so hard to click.  They are used in table of contents of documents with sections and subsections, in navigating a filesystem tree (e.g., Windows Explorer). Also currently in the Blogger post archive by date on the right.

Instead of text on one line, format each section title into a square block of text (wrap, probably at a character level), truncate if necessary.  (It is a separate problem to "truncate" intelligently, for example if all subsection titles begin with the same prefix.)

Place multiple boxes all on one line if they are items all on the same level.  This offsets the loss in vertical are due to each item now taking up more than one line.

Double click to expand or unexpand.

A table of contents that used to be formatted like this (with B expanded):

AAAAAA
BBBBBB
   xxxxxx
   yyyyyy
   zzzzzz
CCCCCC
DDDDDD

would instead get formatted like this:

AAA
AAA
BBB
BBB
   xxx yyy zzz
   xxx yyy zzz
CCC DDD
CCC DDD

This is another application of Fitts's law.