Fwd: Weird tie behaviour when changing Tie_engraver context

[José Luis Cruz]

> If you move the tie engraver from voice to staff, how is lilypond
> supposed to know which voice a tie applies to?  Of course every note in
> the staff will be tied!  This is not a bug.

But one thing is when you create a tie, then it will tied to the next
note of any voice, and different thing is that a tie appears
spontaneously where I I didn't put the ~ sign.

As I see it, if you tie one note, all of the other notes on same
column are tied too, like if all belonged to the same chord. And the
feature of "partially tied chords", introduced in 2.10, didn't worked
when you change the tie_engraver context from voice to staff.

Surely this was an unpredicted case. I could sponsor the changes to
support this behaviour if they are not going to be very expensive.

Here is a simpler example:

\version "2.11.20"
\paper{ ragged-right=##t }
\score {
   << {e''2~ e''2} \\ {c'2 c'2} >>
 \layout {
       \context {\Staff \consists "Tie_engraver"}
       \context {\Voice \remove "Tie_engraver"}
     }
}


Cheers,
Jose