Hover click with pointer events

The pointer event spec currently has no way of expressing a button press on
a hovering pen (https://w3c.github.io/pointerevents/#dfn-chorded-buttons).
There is no allowed value for |buttons| if a pen is hovering with a button
pressed.

This is supported by modern styli, for instance the Wacom Bamboo has a
"Hover Click" feature (described on page 43 of
http://us.wacom.com/~/media/WTC/Files/Manuals/Legacy/Bamboo%20Pen%20Bamboo%20Touch%20Bamboo%20Fun.pdf
).

Is this a scenario we want to enable?

Tim