Second Life Physics Scripting - Pinball #7 - Linked Object Collision Problems

Linked objects caused some interesting problems with collisions for me. On the physics test from the previous post, I had the back wall which pushed the ball unlinked from the rest of the test. When I joined them together it caused the ball to stop at the bottom like it missed a collision and then would not go again until the ball bumped itself.

This wiki on collisions helped me understand the problem.

http://www.lslwiki.net/lslwiki/wakka.php?wakka=collision_start

The problem being that the back wall became the root prim (the one selected last before the Tools/Link was selected). This means it was getting collision events for both the middle wall collision and the base of the system as the same event. Meaning that the collision never stopped so there was no need to send another collision event. I had to add a blank start_collision method to both the middle wall and the table prims. That fixed the problem.