Redisplay bug in 22.1

[Richard Stallman <rms@gnu.org>]

Would someone please DTRT then ack?

From: Joe Wells <jbw@macs.hw.ac.uk>
Date: Mon, 01 Oct 2007 16:31:55 +0100
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Subject: bugs and documentation issues: cursors,
	text/overlay properties (display, before-string, after-string,
	invisible, intangible), column numbers

ISSUE 4:  A before-string property on a range of characters causes
cursor problems.  If point is just before all of the characters
with the before-string property, the cursor is displayed _after_
the string which is the value of the before-string
property.  (This issue was first reported in 2002.)

(progn
  (delete-other-windows)
  (kill-buffer (get-buffer-create "test"))
  (set-buffer (get-buffer-create "test"))
  (insert "AB")
  (let ((o (make-overlay 2 3))) ;; covering the B
    (overlay-put o 'before-string "YZ")
    ;;(overlay-put o 'display "C")
    )
  (goto-char 2) ;; point now between A and B
  (display-buffer (current-buffer))
  )

In the above example, because the characters "YZ" are logically
part of the display of "B", and because point is between "A"
and "B", then logically the cursor should be presented before
the "YZ".