[MlMt] Horizontal thread arcs view

[Eric A. Meyer]

    I'm hoping someone here will be able to make this, or something 
very much like it, happen:

   http://meyerweb.com/area51/mailmate-mockup.gif

I tried editing a custom layout .plist file but all I got (when it 
worked at all) was a great big horizontal thread arcs pane with no 
actual message pane.  Basically, .plists make my head hurt.
    I don't care so much if the separator between the message text and 
thread arcs panes is draggable.  I don't mind having it be static and 
fiddling with the values in a working .plist until I get the size I 
like.  The general layout is the thing I'm after here, and can't seem 
to figure out how to achieve.
    Thanks for any help!

-- 
Eric A. Meyer (eric at meyerweb.com)     http://meyerweb.com/