[MlMt] How to change key bindings in Composer window?

[Mike Hucka]

I've been able to change my key bindings in many Mac applications by 
using a custom ~/Library/KeyBindings/DefaultKeyBinding.dict file, but 
the bindings do not appear to have effect when editing new mail message 
text in the Composer window.  (Or at least, some of the key bindings do 
not work for me as expected.)

I know about, and already use, a MailMate key bindings definition file 
in ~/Library/Application Support/MailMate/Resources/KeyBindings/, and it 
does work -- for MailMate actions outside the Composer window.

Is there a way to affect the key bindings in the editing panel of the 
Composer window?

MH