It would be handy for the DisplayMode setting to allow highlighting of selected SubObjects, right now it is only edges, no mater of what these settings are. It could be a 3rd parameter here:
EDIT: just saw its on the wish/fix pile already per @DanBayn post. Please add my vote for this one then.
https://mcneel.myjetbrains.com/youtrack/issue/RH-34207
–jarek