using show() multiple times: no longer

I have a few scripts that call show() multiple times.
(Why? Well I had pedagogical reasons: I like one
graph to come up at a time in class, in the order
I wish, with no other "distractions".)

These scripts work as I wish if run with execfile() from the
(default Python) interpreter prompt. (I.e., the first
figure is displayed, and when I close it the next is
displayed, etc.) If executed from the cmd line however they
    Fatal Python error: PyEval_RestoreThread: NULL tstate
    abnormal program termination
Can I add something to the scripts so that they behave
as I wish if executed from a cmd line? (Am I wrong to
believe this used to work until recently; say last
version number or so?)

Aside from my wishes, should the script fail in this
fashion (rather than being more gracefully rejected)?
I realize we have been warned against using show()
multiple times ...

Somewhat related:
can I control the order in which figures are displayed
when the show() command is given, or will the highest
numbered figure always display on top?

Thank you,
Alan Isaac
Win 2000, Python 2.3.3, MatPlotLib 0.63