Comment #31 on issue 2783 by [email protected]: wrong placement of timesignature
http://code.google.com/p/lilypond/issues/detail?id=2783
2.15.13 introduced the change in line_count semantics. everything since then overriding 'line-positions may well look ugly.
I thought that a tablature, at least when stands alone, had to signal meter somehow, presumably by time signature. but I'm not a tablature expert at all.
