well you could put a big if inside the balls function and then have all your code within that, then to disable the code, just make the IF false, example
action DestroyBallIfOutsite()
{
while(1)
{
if (BALL_ISACTIVE ==ON)
{
my.pan += 5 *time_step;
// ... all code goes here ...
}
wait(1);
}
}
then you can just toggle the behaviour on and off by switching BALL_ISACTIVE to 1 or 0 ...
oh, just saw pararealist's reply, basically the same idea