Patch: Drop-down List for Identity picking

[Aaron Brown <AaronMB ix netcom com>]

I've always liked a feature of Outlook Express where while you are
composing email, you can select which identity you want the email sent as
in a drop-down list box. So I wrote a patch to implement that idea. I
haven't noticed any problems with it so far(hasn't crashed on me yet ;) ).
The only real issue i've not dealt with is updating the drop-down box when
a new identity is selected via the "Select Identity..." menu item. I would
love to hear constructive criticism as its my first real attempt at using
GTK. The patch is against 1.1.6. Thank you.
-Aaron

dropdown-from.diff.gz