Hi folks--
This is the way you're supposed to get the front window when scripting OmniFocus.
Code:
tell front document of application "OmniFocus"
set theWindow to document window 1
However, what I learned today the hard way is that if you're running from the Script Editor, AND you have the window with your script in it located in a different one of Leopard's Spaces than OmniFocus is running in, this will not reliably return the front window.
Don't know why that is, but I tested it several times and it seems to be true.
Maybe I'll save someone some time.
Best,
David