I was *wrong* about the highlighting limitation I described in the
previous note. I've finally figured out how it works and it does do
what I wanted.
Namely this: by selecting
Tools > Note Type > Highlight [aka ^command 5]
highlighter mode is on and any selected text will be highlighted.
This works well with a graphics tablet, which is great news for me,
and makes highlighting in Skim much more like highlighting a printed
IMO, this leaves the freehand writing of text notes as the main way
that printed PDF notetaking is much superior to skim.