Support for pdf layers?

[Urs Liska]

Hello LilyPonders,

is it possible to think of LilyPond supporting pdf layers, i.e. 
producing output that is distributed on several layers?

The most obvious use for such a thing would be the option to have 
different languages in one document (and the enduser being able to chose 
from by selecting/deselecting layers). Or for teaching purposes 
(documents where you can hide/show solutions, hints or explanations). Or 
show/hide fingerings. Or to produce by default a hidden layer with 
\debugCurvesOn.  (I think the options are numerous).

But I'm even more interested in such a use for scholarly editions.

There have been many experiments and discussions recently in the world 
of musicological editing dealing with options to present the material, 
different readings, different musical sources etc.

Being able to produce layered pdfs could be a major 'selling point' for 
LilyPond. And make it better known in the editorial world.
As I just now experienced LilyPond's potential as a tool for 
collaborative editing, I could imagine that this would be an interesting 
target group.

I don't know how pdf layers work internally, but I imagine it should 
_basically_ be quite simple to create layers and write music on a 
specific layer. This could be entered with a syntax similar to tags or a 
modified \change command.

I am well aware that it wouldn't be trivial at all to deal with the more 
complex implications, especially the question of layers being involved 
in collision handling or not (which would have to be very flexible - and 
therefore at the same time complex).
But for now I'd just like to know if such a thing would in principle be 
considered possible.

Best
Urs

P.S.
Any hints why I don't receive my own posts on this list?
I have of course ticked the option to receive my own posts.
And on lilypond-user I don't have this problem ...