You can input arpeggio signs using the ornaments popover, both during note input and by adding them to existing notes. You can also input arpeggio signs across notes in multiple voices and on different staves that belong to the same instrument, such as piano or harp.
Procedure
Result
During chord input, arpeggio signs are input at the caret position on all staves across which the caret extends.
When adding arpeggio signs to existing notes, they are input to the left of the selected notes.
Arpeggio signs automatically span the pitch range of all notes at that rhythmic position in the current voice during chord input, and all notes in the selected voices/staves when adding arpeggio signs to existing notes.