Changed behaviour of point-and-click

[Urs Liska]

As reported by Mark Knoop in
http://lists.gnu.org/archive/html/bug-lilypond/2016-05/msg00005.html
this commit

commit f30a8189adbbeefa2103e2c2e194040f66bc2291
Author: Urs Liska <address@hidden>
Date:   Tue Jan 19 10:52:33 2016 +0100

    #4747: Remove (all) uses of is-absolute?
   
    The check for absolute paths in  in output-ps.scm
    and -svg.scm is unnecessary because
    (car ly:input-file-line-char-column a-location)
    always returns an absolute, slashified path
   
    Now is-absolute? is not used anymore by LilyPond itself.


has the side-effect of affecting the point-and-click links. If the file
path passed to LilyPond is relative the point-and-click links are
relative as well.

Of course this is an unwanted side-effect of my patch, but I would like
to discuss if this is a feature rather than a bug.

It has been brought up more than once that having full paths in the
point-and-click links *might* be considered a security issue. And much
more important, having relative point-and-click links would make the
files more portable: if you send someone a zip file with .ly and .pdf
files in it relative links would work right out-of-the-box, without
prior compilation. Or if you move/rename a working tree on your computer
the point-and-click-links wouldn't be broken anymore.
On the other hand, if a recompilation is required to make
point-and-click links work, what are they useful for, anyway?

In short: I suggest not to revert the above patch but make the behaviour
configurable through a command line switch.

What do you think:
- revert the patch
- keep the patch
- keep the patch, add configuration option and make relative links default
- keep the patch, add configuration option and make absolute links default
?

Mark, can you give us a reason why you consider relative point-and-click
links "broken"?

Best
Urs