Lunchbox Diamond Panels - Problem with Edge Triangles

Hi,

I'm working on a definition using the awesome lunchbox component library but experience some problems with the edge triangles of the "diamond panel" component. What I want to do is select just the points on the very edge of the surface but if I try to retrieve them with an item component, they seem to change direction around the edge of the surface, if that makes sense.

I attached three pictures, the first one shows the situation as is, the second one the desired selection - the third one shows the little test definition I did to explain the problem.  I'd be grateful for some ideas how to achieve that ...

thanks in advance,

christoph