The text input widget supports deleting text va IME, but the editor does not.
I tried to make the editor widget be able to delete text via IME request:
https://github.com/dcz-self/floem/tree/ime2
It kinda works, but it gets stuck easily because the value of ed.cursor.with_untracked(|c| c.offset()); doesn't change in the same call - and the cursor is expected to move after deletion is complete.