There's a button (+) for adding attachments to a message to be sent, however, I've found no signs of a (-) for removing attachments in case I change my mind.
Another thing, from the point-of-view of final users, is to have the option to write a new message from the 'reading message' window. That is, when I'm reading some message, I don't have the 'new message' button available.
Regards,
-- Eduardo Bacchi Kienetz LPI Certified - Level 2 http://www.noticiaslinux.com.br/eduardo/