Placing grace notes between arpeggios and chords

Arpeggios are positioned by default directly to the left of a chord.

If a chord is preceded by a grace note, you can position the arpeggio in front of the grace note by using an invisible note in a separate voice.

In order to span the two grace notes with the arpeggio, we add the Span_arpeggio_engraver to the Staff context, and set connectArpeggios = ##t.

Here's an example from Chopin's Nocturne No. 11 (Op. 37, No. 2):