[newbie] window groups?

[Ian Zimmerman <itz madbat mine nu>]

Can you explain the concept of window groups in sawfish from the user
(not Lisp programmer) perspective?  What are they good for?

I'm trying to make sawfish align the various pieces of Beep Media Player
(which for a window manager should look identical to XMMS) when it
starts up.  If I don't do anything, the main player window seems to
follow sawfish default policy (in my case, best fit) while the playlist
seems to force itself centered in the workspace.  And unlike XMMS, BMP
doesn't seem to have an option to remember its position, so even if I
manually drag the pieces where I want them, next time it's all wrong
again.

Now, I could define a matcher for each piece and force them to their
exact positions separately.  The only problem with this is that because
these themed windows are so darn special sawfish doesn't display the
coordinates when I drag them, so I have no idea what the precise pixel
positions I want are :(

So I tried to define a group and for each BMP piece, a matcher in that group,
with positioning policy "best fit-group".  But no go, they still break up.
So I'd like 2 kinds of answers: explanation what groups are about and advice
how to accomplish my very important goal.

I hope I'm making sense.

-- 
Experience with Asset Control an asset.