Re: Overlay property "display"
Jerry James <james(a)xemacs.org> writes:
There has been some work on hideshow.el in the Emacs sources
recently. Since I did the port to XEmacs using extents, I thought I
should try to mirror these changes. Some of them take advantage of
the "display" overlay property. I'm having a hard time
understanding this property.
It says how the content is to be displayed, like a face property would
do. In contrast to the face property, the original content completely
gets _replaced_ by what the display property specifies, at least for
most types of display property (there are several different ones).
Have any of you encountered it before and, if so, do you know what
its XEmacs equivalent (if any) would be?
XEmacs has no equivalent. Whatever substitute you could come up with
under XEmacs has the fundamental difference that you can't place point
or the cursor onto it.
An approximation for the most common 'display property usage (there
are a number of different possibilities, read up in the Elisp manual)
would be to place an extent, mark it as invisible and place the
replacement glyph (which has quite more possibilities in Emacs) as an
_end-glyph_ on the extent (placing it as a begin-glyph is no option
since begin-glyphs happen to turn invisible along with the extent. It
is shere luck that the end-glyphs don't do the same).
That's in case the display property is something displayable on its
own. There are a number of other functions it can be used for,
however.
--
David Kastrup, Kriemhildstr. 15, 44793 Bochum