Tremolo strokes collide with ledger lines
Steps to reproduce:
1. Create notes which need 3-4 ledger lines above the staff.
2. Add single-note tremolos.
Expected result: tremolo strokes should stay within the stave
Actual result: tremolo strokes collide with the ledger lines
From Elaine Gould's reference book "Behind Bars", page 222:
"Tremolo strokes must stay within the stave so as not to be confused with, nor collide with, a ledger line."
This will require a fix which lengthens the note stem if the note is stemmed.