Getting subprocesses to be hidden on Windows

[geoffbache]

OK, more background needed. I develop the TextTest tool which is a
generic test tool that starts tested applications from
the command line. The idea is that it can handle any system under test
at all, whatever language it's written in. Preferably
without requiring a bunch of changes to the tested code before
starting. I'd like to be able to pass some sort of flag to
ensure that the system under test *and everything it starts* remain
hidden.

I can do as you suggest in my PyGTK GUI, of course, but that's only
one system under test. A generic solution, if there
is one, would be much better. I felt like there ought to be one
because :

a) It's easy on UNIX and
b) I managed to hide the system under test fairly easily, just not its
child windows and dialogs.

Thanks for the help, anyway, it's another fallback if I can't find a
solution.