bug#397: 23.0.60; T in Info when in (dir)

[Drew Adams]

`T' in Info when you are at the directory level (dir), should either
raise an error or DTRT.
 
To DTRT, it could do either of these:
 
- return to the directory listing (which is useless),
  which is the top-level TOC
- show the contents of all manuals (pretty costly),
  which is the detailed TOC
 
Currently, what `T' does is worse than useless. It shows this, where
(dir) and the second Top are links to the same place - the directory
you just came from:
 
 Up: (dir)
 File: toc,  Node: Top
 
 Table of Contents
 *****************
 
 Top.
 
This is not only useless; it is wrong. Top cannot be the same thing as
(dir), but both links lead to the same place. And the Top listed as
the current node is different from the destination of the Top link.
 
Please, at a minimum, (1) raise an error if `T' is used in the
directory (dir), and (2) disable (dim) the corresponding item in the
Info menu when in (dir).
 
 
 
In GNU Emacs 23.0.60.1 (i386-mingw-nt5.1.2600)
 of 2008-05-29 on LENNART-69DE564
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --no-opt --cflags -Ic:/g/include
-fno-crossjumping'