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elisp's display.texi: What happens to overlays when text is inserted/del


From: Alan Mackenzie
Subject: elisp's display.texi: What happens to overlays when text is inserted/deleted?
Date: Sun, 18 Jan 2004 18:38:25 +0000 (GMT)

Elisp manual's display.texi.  Section "Overlays".

In Emacs, when text is inserted into/deleted from a buffer in which an
overlay exists, the overlay's beginning and end are updated much like
markers are.

The Elisp manual (display.texi) doesn't say this explicitly - I think it
should.

Attached is a patch to display.texi which adds this info, and a ChangeLog
entry.

-- 
Alan Mackenzie (Munich, Germany)

*** display-1.111.texi  Fri Jan 16 20:36:33 2004
--- display-1.111.acm.texi      Sun Jan 18 18:00:51 2004
***************
*** 966,971 ****
--- 966,978 ----
  beginning and end.  It also has properties that you can examine and set;
  these affect the display of the text within the overlay.
  
+ If text is inserted into or deleted from the buffer before the range
+ covered by an overlay, the beginning and end of the overlay are
+ automatically adjusted so that it continues to cover the same range of
+ text.  Similarly, if text is inserted into or deleted from the inside of
+ the range covered by an overlay, the overlay gets expanded or shrunk
+ accordingly by adjusting its end position.
+ 
  @menu
  * Overlay Properties::  How to read and set properties.
                        What properties do to the screen display.
2004-01-18  Alan Mackenzie  <address@hidden>

        * display.texi: Note that when text is inserted into/deleted from
        a buffer, any overlay's beginning and end positions are
        automatically adjusted.


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