onstop subroutine_name()

Causes the subroutine to be executed when the stop button is pressed. If the subroutine is allowed to return, the program will continue running as if not stopped.

onstop handleStop()

subroutine handleStop()
	x = confirm("stop program")
	if x then end
end subroutine

for t = 1 to 10
print t
pause 1
next t

print 'done'