The message panel shows a single mail message.  You can fill
it by using the retr button or by double-clicking on one  of
the messages in the above message list.

The message is a general-purpose tk text widget, and you can
edit it or copy and paste to and from it.  At present, there
is no way to save it to a file other than copy-and-paste.

If you resize the window, the message panel will use up  all
the bottom portion.