Stopping a script

[Richmond]

I have a *button* which, when I click on it, sends a *graphic object* 
off on a mad journey all over
a *card* based on reading positions from a*listField*.

I have tried *STOP MOVING* to interrupt that script, but that does *NOT* 
work
because the graphic is executing a large number of very short movements 
in a cycling
*REPEAT UNTIL* structure.

Ideally (Ho, Ho, Ho.) I should like to be able to have something like this:

the mad movement script starts executing when triggered by a 
*mouseEnter* script
in the *graphic object* that moves,

and

some sort of *STOP SCRIPT* in a *mouseLeave* script in the same *graphic 
object*.

Now, I know that sounds a bit *bonkers*, but I am writing this on behalf 
of a very bright chap
who is attending my Summer classes, and I do understand what he is 
trying to achieve.

Richmond.