Being a Lilypond newbee, I want to check with you if this is possible:
I want to create an inivisble "sync part" with "sync noteheads" drawn in white.
Main reasons:
The invisible white noteheads of the "sync part" should produce clickable links in the output pdf. These links, and their coordinates on the the pdf-page, could be used as a basis for syncing a graphical moving pointer to a wav playback of the example. (I'm using a midi to wav for converting, so I know what the playback position of the notes are in the wav file...)
The invisible "sync part" could produce a metronome click midi track.
I would prefer the "sync part" to NOT affect the x-spacing of the visible parts. Have a look at the jpg file, hopefully it should make things clearer.
InvisibleButClickableSyncPart.jpg