I've seen one around, but can't find it anywhere, any more. It will make the vertices in a curve stand out. MacOS10.10.9 Yosemite, SUMake2017.
Turn on endpoints in the styles dialog.
Boy, that was quick and easy... Thanks a bunch!
Well, actually...Turns out it's not that simple. Clicked the "endpoints" box, but nothing happens. Where's a good place to learn more about styles? YouTube tutorials aren't much help in the matter.
increase size... and be aware that endpoints are shown for edges only, for arcs/circles/curves you need to explode them to see.
The user guide chapters on styles:http://help.sketchup.com/en/article/3000107