open stepper, make sure it works for (+ 3 4).  Make sure it only works
for the language levels it's supposed to.  Make sure that you get a warning
when you change the underlying program, and a warning when the program 
window disappears. Try stepping backward and forward through programs with correct
and erroneous (syntax errors, runtime errors) executions.  Make sure that the 
buttons are enabled and disabled as necessary.  Try programs which print snips
(print-convert-test.ss)

