Re: tabulated-list-init-header and glyphless-char-display

[Chong Yidong <cyd@stupidchicken.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> For instance, if you do (aset glyphless-char-display ?a 'empty-box),
>> that tells Emacs that "a" is a glyphless character, and causes all
>> "a"'s to be displayed as empty boxes.
>
> That's right, but why would you do something like that with a
> characters that is perfectly displayable?  You should only do that
> with characters that cannot be displayed, like unencodable characters
> on a tty.  That's what I was trying to convey; sorry if I failed to
> get that across.

I think what you have in mind (correct me if I'm wrong) is to do some
kind of terminal detection, and then conditionally set up the
glyphless-char-display char table in the tabulated-list buffer.  That
solution is not satisfactory, because it won't work in the multi-tty
case.  The same buffer might be simultaneously displayed on a text
terminal and on X, and we want the X display to work properly.

The correct fix is to provide some way to say "in the no-font case,
display this character in this way".  There's currently no multi-tty
compatible way to do this for one specific character.

An alternative to my earlier text-property-based proposal is to extend
glyphless-char-display's extra slot, so that in addition to the symbols
`hex-code' and `empty-box', it can hold yet another char table for
resolving the display of individual fontless characters.

However, this has the undesireable (though minor) side-effect of
changing display in the main part of the buffer, so I still prefer the
text-property-based solution.