Re: Info mutilates user overlays.

[Luc Teirlinck]

Stefan Monnier wrote:

   Please: *how* do you highlight ?
   Did you create some commands similar to what is available under M-g
   but using overlays, or do you add the overlay from a hook, or ...

The user would use some interactive command, say 
`M-x scan-buf-char-property-regions', or a key sequence bound to it.
I have a command `scan-buf-update-char-region-overlays' that updates
_all_ highlighting produced by the previous and similar commands, in
the accessible portion of the current buffer.  (Except that I still
have to make the updating work better for narrowed buffers with
different pieces highlighted differently.)  Maybe just adding the
updating command to the right hook might solve the problem.  I will
take a look whether any hook is automatically called in the given
situation.  Otherwise, the user could call the updating command, if he
wants the highlighting restored.

I keep track of the overlays by giving them a "private"
'scan-buf-char-property-regions property, so I know which overlays
were made by the function and I can delete them as necessary.

The highlighting is actually _meant_ to be temporary (to get an idea
of which text properties are present in the buffer), but it is
somewhat inconvenient if it disappears after, say, quickly following a
reference and then a quick `l' to get back.  As I said though,
updating everything is convenient for the user and could be made
automatic using some hook.

I could set a timer, but in read-only buffers that would lead to a lot
of completely needless deletion and re-creation of overlays, generating
garbage to be collected and it will normally be obvious to the user
when the buffer has changed and needs to be updated.

Sincerely,

Luc.