bug#29720: 24.5; doc string of `invisible-p'

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

The doc string is unclear.

  "Non-nil if the property makes the text invisible."

What property?  What text?

  "The non-nil value returned can be t for truly invisible text or
   something else if the text is replaced by an ellipsis."

Huh?  What is "truly invisible"?  What "something else"?  Does
"something else" include `nil'?  What does it mean for the text to be
replaced by an ellipsis?  What does the (unspecified!) value signify in
the case of "the text" (?) being "replaced by an ellipsis"?

It's really not clear what this doc string is trying to say.

This text was introduced in Emacs 23.  Prior to that the text was clear:
"Return non-nil if the character after pos is currently invisible."




In GNU Emacs 24.5.1 (i686-pc-mingw32)
 of 2015-04-11 on LEG570
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/usr --host=i686-pc-mingw32'