bug#20483: 25.0.50; Customize buffer `Show' for whole option: return previously shown display

[Drew Adams <drew.adams@oracle.com>]

You can consider this an enhancement request.  Essentially, it removes
control by the main hide/show button from deciding what gets shown wrt
the doc string.  It gives that doc-string control only to the other
hide/show button, which is designed for doc-string visibility control.

emacs -Q

M-x customize-option blink-cursor-mode

By default, everything is shown.  There are two `Hide' buttons:

1. At the far left, to hide everything other than the option name and
   the first line of the doc string.
2. After the first line of the doc string.

Click #1, to hide (almost) everything.  That button changes to `Show
Value', and the other `Hide' button changes to `More'.  Which is OK (but
see below, about the name of button `Show Value').

Click #1 again.  It should return to the previous state, but button #2
still says `More' and the rest of the doc string is still hidden.

IOW, #1 should toggle between hiding (almost) everything and returning
to whatever was shown before it was clicked to hide stuff.

Another way to see that this proposed behavior would be better:

Click the `More' button (#2), to show all of the doc string.  Then click
#1, to hide (almost) everything.  Then click #1 again.  A user would
reasonably expect it to show what was last shown wrt the doc string,
i.e., the full doc string.  IOW, #1 should not decide what it *shows*,
wrt #2 (but it is OK for it to decide what it hides).

If this gets fixed as described then `Show Value' should be renamed just
`Show'.

The main hide/show button (#1) should toggle between (a) hiding
everything except the option name and first doc line and (b) showing
everything, except as last decided by button #2.  This lets the user use
#2 (and only #2) to decide about the doc string display, and use #1 to
hide a maximum of stuff.

In GNU Emacs 25.0.50.1 (i686-pc-mingw32)
 of 2015-04-05 on LEG570
Bzr revision: 16eec6fc55dcc05d1d819f18998e84a9580b2521
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --host=i686-pc-mingw32 --enable-checking=yes,glyphs'