musescore/MuseScore — pull request #1503 by MarcSabatella (2014-12-03 16:53:40+00:00)
Title: fix #40581: overlapping ledger lines between voices

My fix aims for a balance betwene efficiency and effectiveness. In determining if there is a conflict with a previous note, I always prefer a note in the same voice if there is one in the previous segment. Only if there isn't do I look in other voices. I tried variations where I always hunted for chord with ledger lines in any voice, but there would still be corner cases that were missed, so I went with the simple version.