Features of PolyDraw
1. User can draw any number of polygons.
2. Polygons can be open or closed.
3. User can select groups of points, not necessarily belonging to a single polygon. Groups of vertices can be moved together or deleted all at once.
4. Polygons can be colored with any RGB color available.
5. Vertices can be constrained to lie on grid intersections.
6. The grid spacing is adjustable.