Re: Should invisible imply intangible?

From: "Stefan Monnier" <monnier+gnu/emacs@RUM.cs.yale.edu>
Cc: monnier+gnu/emacs@rum.cs.yale.edu, emacs-devel@gnu.org,
	David.Kastrup@t-online.de (David Kastrup)
Subject: Re: Should invisible imply intangible?
Date: Tue, 12 Mar 2002 12:56:16 -0500	[thread overview]
Message-ID: <200203121756.g2CHuG514941@rum.cs.yale.edu> (raw)
In-Reply-To: 200203111906.g2BJ6BY04591@wijiji.santafe.edu

>     >     I could agree to it but only in the case where the screen representation
>     >     is really empty, so that both cursor positions are displayed in the same
>     >     way.
>     > 
>     > That is the case we are talking about.
> 
>     I do not know how to detect that case robustly.
> 
> Whenever the text is invisible and does not display an ellipsis.
> The value of TEXT_PROP_MEANS_INVISIBLE will tell you whether this
> is the case.

That much I know, but the problem is when there's some other property
like a `display' property that ends up displaying something.

>     But some texts can have both an image and the invisible property.
> 
> Shouldn't that make the image invisible?  The image property should
> have no effect when the text is invisible.  (It doesn't matter what
> the text wou;d looks like, if you don't see it.)
> 
> Is that not what happens now?

It seems not since David uses display+invisible when replacing TeX source
code with an image of the output in his preview-latex package (the `invisible'
property seems useless at first, but he uses it so he can use the
isearch-open-invisible hook).

>       In my experience
>     most cases where I encounter invisible text (and where point can easily
>     end up inside the invisible text) is with things like outline-minor-mode
>     and hs-minor-mode (i.e. text replaced by ellisps), so that's what I consider
>     as the most important case to handle.
> 
> What you want is right for that case, the case where an ellipsis is
> displayed.  I am talking about what to do in the other case, the case
> where the text is not replaced by an ellipsis.
> 
>     It looks like you have another kind of scenario in mind, but I don't know
>     what it looks like.
> 
> The scenario is one where message header lines are marked as invisible
> using overlays, the goal being to hide them.

Any reason why those cannot explicitly use the `intangible' property ?

	Stefan

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