bug#869: Bug in handling invisible text, and bug in Pmail.

[Paul Michael Reilly <pmr@pajato.com>]

Stefan Monnier wrote:
>> I don't think it is that simple because "that text" is simply part of
>> the collection of headers, some of which have been specified to be
>> invisible as Emacs displays the message, i.e. the X-Coding-System:
>> header can, according to rfc2822, precede or follow the Date: header.
>> This, if I understand the issue and your desires properly, makes
>> setting the buffer boundaries a non-workable solution.  I don't know
>> what the right solution is yet.  Worst case, the issue is an
>> indictment of using invisible text to hide the headers.  Yuck.
> 
> But is that specific to Pmail?  I.e. doesn't Rmail use the same
> texhcnique (or even code) to hide the headers?
> If Pmail is indeed different, could you explain to me why Pmail had to
> change this part of the code?  It seems unrelated to babyl-vs-mbox.

Apparently, Rmail/babyl rearranges the headers and then sets the buffer 
boundaries, thus eliminating the problem.  Rmail/mbox could have (and 
probably should have) used the same approach.

Now however, it is pretty clear that a presentation buffer is in order 
to deal with the coding issue, something I ill understand today but I'm 
gradually picking up.  I also think that the coding issue implicitly 
means better MIME handling within Rmail.  Not hardly a bad thing, 
especially given modern Emacs' improved graphic capabilities.

-pmr