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To: xemacs-beta@xemacs.org
Subject: Re: Xemacs text-property-bug with insert?
References: <rjg1v2pwpc.fsf@zuse.dina.kvl.dk> <QQcsbs15258.199706011714@crystal.WonderWorks.COM>
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From: David Moore <dmoore@ucsd.edu>
Date: 02 Jun 1997 13:39:02 -0700
In-Reply-To: Kyle Jones's message of Sun, 1 Jun 1997 13:14:31 -0400 (EDT)
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Kyle Jones <kyle_jones@wonderworks.com> writes:

> Text properties are implemented with extents under XEmacs.
> The faces of overlapping extens are merged for display, which
> explains what you see in your example.
> 
> Further, if you call (get-text-property 7 'face) in the overlapping
> region you get an incorrect answer.
> 
> So yeah, the text property emulation is broken.  How broken, you
> really don't want to know.
> 
> "Would you like to fix it?" says Kyle, with a stupidly hopeful grin.

I've been slowly (between classes) reworking some of the text-prop
interface to extents, mostly for performance reasons.  Several routines
are significantly faster now[1].  So, if you have good examples of broken
things, I'll see what I can do at the same time.

I'm also planning to do something about xemacs lack of understanding of
front-sticky and rear-nonsticky, since Pers mentioned that to me.

Under no circumstances do I want to see text-properties implemented
independently of extents, as that'd make a maintainence nightmare.  But
a lot of the existing text-prop on top of extents interface is a poor,
and can be improved.

Footnotes: 
[1]  Looking like about 10x speedup for text-property-any.  Gnus
groupies rejoice, this is a majority of the group exit cost (especially
with virtual groups).

