RE: "What's This?" in Describe submenu

[Drew Adams]

    In its current form, it does IN NO WAY resemble what a Windoze user
    would expect from the "What's this" function.

    When you click on the "What's this" function in Windoze (typically not
    available as a menu item, but as a [?] icon), the cursor changes shape
    to an arrow with a question mark, and then the user can (in principle)
    click on anything in the application window to get help for that item
    (typically an input field).  So it gives help for _visible_items_, not
    key bindings!

    If we want to keep the "What's this" menu item, then we should implement
    it properly, and not provide something completely unrelated.

FWIW, I wrote such a command - perhaps it can serve as food for thought. It
works in Emacs 20 - I haven't yet ported it to 21. It does not change the
mouse cursor to a question mark (I wasn't sure how to do that), but that
would help indicate the usage. When the command is run, the prompt is "Click
mouse on something or type a key sequence".

The code is here: http://www.emacswiki.org/cgi-bin/emacs/help+.el. I place
the command, called `help-on-click/key', in the Help > Describe submenu, and
call it just "This" (so, Describe > This).

Here is the doc string:

 Give help on a key/menu sequence or object clicked with the mouse.
 The object can be any part of an Emacs window or a name appearing in a
 buffer.  You can do any of the following:

    type a key sequence (e.g. `C-M-s')
    choose a menu item (e.g. [menu-bar files open-file])
    click on a scroll bar
    click on the mode line
    click in the minibuffer
    click on an Emacs-related name in a buffer: apropos is called
    click anywhere else in a buffer: its modes are described

 Help is generally provided using `describe-key' and the Emacs online
 manual (via `Info-goto-emacs-key-command-node').  If no entry is found
 in the index of the Emacs manual, then the manual is searched from the
 beginning for literal occurrences of KEY.

 For example, the KEY `C-g' is not in the index (for some reason), so
 the manual is searched.  (Once an occurrence is found, you can
 repeatedly type `s' in *Info* to search for additional occurrences.)

 If you click on a name in a buffer, then `apropos-documentation' and
 `apropos' are used to find information on the name.  These functions
 are not used when you do something besides click on a name.

 If you click elsewhere in a buffer other than the minibuffer, then
 `describe-mode' is used to describe the buffer's current mode(s).