If I have an existing highlight and add a note to it, the resource does not display the note icon automatically. This means that the note is effectively invisible from my resource, because I cannot hover over the highlight and see the note. It is not even clear that there is a note at that location.
I appreciate the ease of changing the note icon, but I should not have to manually select a note icon when I add a note to what started out as a highlight.
By the same token, if I delete my note but retain the highlighted text, I would like to see the note icon disappear from the resource, so it becomes a pure highlight rather than an empty note.