Re: Problems with info (emacs version)

[Luc Teirlinck]

Simon Josefsson wrote:

   I'd say this is a bug in the mail sending part of Emacs.  Message asks
   the user if she knows about the hidden parts.

It does not seem to do that in the concrete example I gave.  I am not
terribly familiar with message-mode (I use mail-mode), but
message-mode does not seem to check for or ask about the display
property.  Also, to respond to Miles, the invisibility property is
already in yank-excluded-properties.  There is no "invisible" text
around in the example (that is there are no invisibility properties
around), only text you can not see, because it has the display
property.  message-mode behaves the same as mail-mode in the example,
without any warning, although it does seem to get the FCC correct.

I should say that a proposed change by Stefan would get rid of the
very concrete problem with info I showed.  But even with the
invisibility property, which is in yank-excluded-properties by
default, problems remain when a user yanks a larger piece of text into
a mail buffer or first saves the text to file, then inserts the file
(which I sometimes do).  The user may not carefully double check the
yanked or inserted text, because he "knows" (or believes he "knows)
what is in there.

   > Do you consider the above a "real" problem?  I do.

   Me too, but I don't think the problem is with info.

I do believe that there are two problems with info.

One would be eliminated by a change proposed by Stefan.  That problem
is that I believe that it uses the display property in an
inappropriate way.  The display property is nice to make the text
"appear differently" (but with the same content), to make a whitespace
string display a picture and similar, but I believe that the following
info-style use is inappropriate:

You have a file.  You want to make some text in the file invisible,
but at the same time you also want to do some aligning.  Hence you
give the text a whitespace string as display property.  The result is
"visible text that you just can not see".  You trick the user, you
trick all Elisp code dealing with invisible text, including message
mode's warning mechanism.

The second claim I am making is that if you present the user with a
buffer containing invisible text, you should always make sure that the
user is aware of the invisible text and provide him with a convenient
(even for less sophisticated users) way to make that text visible.
Otherwise plenty of problems could occur.  I proposed to bind a
visibility toggling command to, say, `v' in info.

Sincerely,

Luc.