arpeggiate across voices [bug + enhancement]

This is relatively common in piano publications. Assume the first voice is two beamed eighth notes across the duration of a quarter note in the second voice (together, they form a three-note chord). Here is an example: test-multivoice-arpeggiato.mscz.

1. first, the problem:

   Select only the first voice chord (the 1st set of eighth notes). As evinced by the selection box, which only extends the duration of an eighth instead the full quarter beat, the second voice is not selected. Now add an arpeggiato. Musescore adds two arpeggiatos - two squiggly line symbols - one per voice. This is problematic.

2. now, the enhancement:

   Select the entire chord across both voices - the 1st set of eighth notes and the quarter note. As evinced by the selection box, which extends the full duration of a quarter beat, both voices are selected. Now add an arpeggiato. Musescore adds two arpeggiatos. Instead, I would like musescore to add a single arpeggiato, shared across both voices.

   There is an imperfect workaround:

   • copy the second voice note to the first voice's chord (the duration will be shortened from 1/4 to 1/8).
   • mark the copied note as invisible (but keep it playable)
   • delete the original copied note from the second voice (if you don't do this before adding the arpeggio, you will encounter the problem I described in [1]).
   • arpeggiate the chord with the extra note
   • re-add the deleted note from the second note, with the appropriate duration. Mark it as non-playable (but keep it visible)

   This is imperfect because the playback duration of the shifted note has been truncated. Also, it's very complicated.