[13.5] Can I stop the user from closing my MIAW?

Yes. Try putting the following as a movie script in the movie you are opening as a MIAW:

global myWind 
-- ideally this needs to be set when the MIAW is opened
-- by the stage, though there are various kludges to 
-- work it out otherwise

on closeWindow
  open myWind
end closeWindow

[Thanks to Paul Farry <p.farry@cqu.edu.au> for this suggestion]