Comment #2 on issue 2536 by [email protected]: Patch: Make \footnote work via \tweak
http://code.google.com/p/lilypond/issues/detail?id=2536
Ok, here is the first problem: changing TimeSignature. This grob is an indirect consequence of a change in Timing properties, consequently its cause is #'().
It would seem like a natural fit to forget about the ultimate_event_cause stuff in \tweak. Instead, when grob types are specified, \footnote works as previously, possibly using a FootnoteEvent. However, this glosses over the fact that \footnote _does_ receive a music argument which would then disappear. It would need to be something that can disappear without problems, perhaps even #'() or \default.
Another possibility would be to introduce a way in which \tweaks can travel to indirectly created grobs, like that of \time or \clef. That would be ultimately more elegant and understandable. However, it would be piecemeal work. If the first option is implemented, one can do the second option by and by.
Why does life need to be so complicated?
