Still playing around with this, mostly added the editing functions (Add,Delete,Insert,Move). Very tempted to throw a bit of GUI on it. The down side would not doubt be that simple 'as is' tool could easily blow out into be time hungry project. Really don't have time for that atm.
Since this tool is for collision mainly (but I guess you could draw shapes with it if you wanted.) You don't actually (at this time) edit the shape directly. Rather, you edit a POLY LINE list. The verts in the polyline list are expected form a closed concave polygon. These points should be order CLOCKWISE...
Once you have your area defined how you want it, you then merge this Polyline with the collision Shape. You can keep doing this as many times as needed. So you can define various areas that are solid or areas inside areas etc.
It's not most the flexible tool in the world and i can think of a many features that would be handy to have in, that are missing, but it works. Which is a first step
This piccy shows the collision shape built from various polylines, creating a kind of negative shape
http://www.playbasic.com