Ah, awesome smile I was used to the old $onpoly() and $inpoly() and had issues with passing fully closed polygons so I always assumed it required a clockwise or counter-clockwise point definition, and not contain any identical points, so it's last check with the last points would be a segment between the last point passed, and the very 1st point passed completing the polygon.

I thought this was by design, so none of my polygons are fully closed, due to the behavior of the old methods. You can see this when I draw the polygons to the screen, I pass the polygon to drawline with also adding the very 1st point from the polygon so drawline draws a completed polygon.

Example:
drawline -n @OnpolyTest 0 1 %poly $gettok(%poly,1-2,32)