Devendra,
If there are (say) two buttons in your button box, it would be:
?callback list("funcA() funcB() funcC()" "funcD() funcE() funcF()")
When the first button is pressed, it will execute funcA(), then funcB(), then funcC(), and when the second button is pressed - well, I'm sure you can guess. All that you'd done is built a sequence of functions to be executed.
Regards,
Andrew.