problems with partcombine

[Orm Finnendahl]

Hi,

 below is another example with a couple of issues I can't resolve:

The issues:

1. With my lilypond version the clef change to the bass clef in the
   second bar is ignored (although in other situations a clef change
   in mid bar is printed).

2. All rests in the second bar of musictwo are not shown.

The second issue seems to happen, when one of the two partcombined
voices starts with a rest (especially if it is a multimeasure rest,
where it makes complete sense to suppress it), but this behaviour is
not consistent and I couldn't yet find a pattern or a reason where it
happens why and how to avoid it. In addition these rests (especially
multimeasure rests if displayed) often collide with music of the other
part in partcombined staffs. I guess this still is an unresolved issue
in lilypond but it would help a lot if someone who knows why it
happens could give me some explanation to better deal with it.

Yours,
Orm



\version "2.19.5"

musicone = { < b' >8 < e'' >8~ < e'' >8 r4.  | % 48
             r2. \tag #'score \clef "F" r8 < cis! >8~ \ff < cis >8 < g >8~  | % 
49
           }

musictwo = { \time 3/4 < gis'! >4 < cis''! >4 < g'' >4  | % 48
             \time 5/4 < c''' >4 r2 r2 | % 49
           }


{ \new Staff { \clef "G"
               \partcombine
               { \keepWithTag #'score \musicone }
               { \keepWithTag #'score \musictwo }
             }
}