I've used MC for small projects, but never used configurations.  Did
they even exist in 3.8?  This is the first I've heard about them.
Since I've used Envy and Store, it is pretty easy to guess what they
are for.  But it would be nice to have a little documentation.  I
found some e-mail and blog posts discussing MC configurations, but no
real documentation.

3.9 comes with a MC Configuration editor, so I am guessing that
configurations are fairly new.  It would be hard to figure it out by
trial and error.  The 3,9 MC user interface is wretched.  It is much
harder to figure out than the old interface.  The MC user interface in
3,7 and 3.8 was not great, but not bad.  The UI in 3.9 is not only
ugly, it is confusing.  I gave up on it.

-Ralph Johnson