[Emacs-diffs] emacs/doc/lispref display.texi

[Eli Zaretskii]

CVSROOT:        /cvsroot/emacs
Module name:    emacs
Changes by:     Eli Zaretskii <eliz>    09/04/11 08:54:10

Modified files:
        doc/lispref    : display.texi 

Log message:
        (Overlays): Overlays don't scale well.  See
        http://lists.gnu.org/archive/html/emacs-devel/2009-04/msg00243.html.

CVSWeb URLs:
http://cvs.savannah.gnu.org/viewcvs/emacs/doc/lispref/display.texi?cvsroot=emacs&r1=1.41&r2=1.42

Patches:
Index: display.texi
===================================================================
RCS file: /cvsroot/emacs/emacs/doc/lispref/display.texi,v
retrieving revision 1.41
retrieving revision 1.42
diff -u -b -r1.41 -r1.42
--- display.texi        9 Apr 2009 01:17:09 -0000       1.41
+++ display.texi        11 Apr 2009 08:54:08 -0000      1.42
@@ -1148,6 +1148,14 @@
 beginning and end.  It also has properties that you can examine and set;
 these affect the display of the text within the overlay.
 
address@hidden scalability of overlays
+The visual effect of an overlay is the same as of the corresponding
+text property (@pxref{Text Properties}).  However, due to a different
+implementation, overlays generally don't scale well (many operations
+take a time that is proportional to the number of overlays in the
+buffer).  If you need to affect the visual appearance of many portions
+in the buffer, we recommend to use text properties.
+
 An overlay uses markers to record its beginning and end; thus,
 editing the text of the buffer adjusts the beginning and end of each
 overlay so that it stays with the text.  When you create the overlay,