[feature request]: PDF layers - for optional fingerings etc.

[Boris Dusek]

Hi,

I came across sime nice idea for LilyPond: it should be possible to use PDF 
layers conveniently for optional content - e.g. fingerings and dynamics.

For example, consider the following case: you submit a piano score to mutopia 
project, which is some original version without fingering and dynamics. But 
you have invented your own fingering and want to include it in the score 
(since it may be convenient for others who might not be able to figure out a 
suitable fingering), but also do not want to force it into the score, since 
it might confuse others who already have their fingerings.

The solution is to have the fingering in a PDF layer - user can toggle 
layer's visibility (and printability). The same for dynamics, slurs, and so 
on.

For those who want to read something introductory about PDF layers (and 
especially download example PDFs files with layers), I found an article at 
http://www.planetpdf.com/creative/article.asp?ContentID=6527
The downloadable examples at the bottom of that page demonstrate the power of 
PDF layers. What might be of interest is that I found there that PDF layers 
are part of PDF version 1.5

Another case is if you have two variants of dynamics (or fingering) and want 
to include both, the viewer chooses which one (if any) is better for him/her.

Maybe each engraver should have its own PDF layer? (just a brainstormed idea 
for discussion)

Finally, I can't sponsor this, but would like to kindly ask the maintainters 
to put this as a feature seeking sponsor(s), maybe after others discuss this 
on the mailing list, since the idea is raw and further suggestions are 
welcome.

Regards,
Boris Dusek