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To: XEmacs-Beta@XEmacs.org
Subject: overlays
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Date: Wed, 15 Jan 1997 13:45:45 -0500
From: Joe Nuspl <nuspl@nvwls.cc.purdue.edu>


I have changed the overlay package so that it does not use the
obsolete mechanism.

I would like some input on the following points:

1) overlay-buffer returns the buffer that the overlay (extent) is in,
   but extents can be over strings or buffers.  There are two ways of
   implemented the function:

	(defalias 'overlay-buffer 'extent-object)

   -or-

	(defun overlay-buffer (ov)
	  (let (obj)
	    (if (not (bufferp (setq obj (extent-object ov))))
		(setq obj nil))
	  obj))


2) overlays have a concept of a center point, overlays-in returns two
   lists, one with all of the overlays before the center point and one
   with all those after the point.  The Gnu Emacs buffer structure has
   a member, overlay_center, that contains the point.  I thought of
   making a buffer local variable for this.


3) Should this be something that is required or that is dumped?


