Changing point color?

Questions
1

Continuing the discussion from Making a Polygon Disappear:

For the next slide I don’t want to fill the circle with triangles. It would be cleaner if the movable point could change color or give some other indication that it’s in the correct location. Ideas?

2

Make multiple polygons that conditionally display (i.e. put restrictions)

3

Can a polygon have only one point?

4

As far as the polygon function is concerned, yes.

5

Thanks for reading between the lines. That’s exactly what I meant. I appreciate your help!