Re: hiding lines

[Alan Mackenzie]

Hi, Stefan!

On Thu, Apr 02, 2009 at 08:39:50PM -0400, Stefan Monnier wrote:
> > The following makes the current region invisible and intangible.  It

> I'll just remind people that I strongly discourage the use of
> the `intangible' property.  Your code should work well with just the
> `invisible' property; if not, it might be a bug.

I don't know exactly what `invisible' and `intangible' text/overlay
properties mean.  I don't know when to use each of them, when to use
both of them together.  The documentation is vague and unhelpful.  It
doesn't define these properties, instead merely stating _some_ of the
things they do.

For example, the documentation implies that if I isearch for something
inside the invisible bit, the cursor should end up on the other side of
the invisibility.  Instead, it does the Right Thing.

"Invisible" means you can't see something.  "Intangible" means you can't
touch it.  However, the `invisible' property has bits of intangibility
mixed in with it.  This makes it very confusing.

It seems though, at least in C Mode, that when a user makes part of his
buffer invisible, the invisible bits are still seen by the parsing
routines in CC Mode.  I don't know why this is so.

The documentation, (Elisp manual pages "Invisible Text" and "special
properties") is of no help here.  It says, in effect, "The invisible
property sort of does this".

Are there any complete descriptions of these properties anywhere?  Are
there any guidelines for there use anywhere?

>         Stefan

-- 
Alan Mackenzie (Nuremberg, Germany).