Smart Key - Email Readers

If pressed within a Hyperbole-supported mail reader (defined by
‘hmail:reader’) or a mail summary (defined by ‘hmail:lister’) buffer:
  ACTION KEY
     (1) in a msg buffer within the first line of a message or at the
         end of a message, the next undeleted message is displayed;
     (2) in a msg buffer within the first line of an Info cross
         reference, the referent is displayed;
     (3) anywhere else within a msg buffer, the window is scrolled up
         one windowful;
     (4) in a msg summary buffer on a header entry, the message
         corresponding to the header is displayed in the msg window;
     (5) in a msg summary buffer, on or after the last line, the
         messages marked for deletion are expunged.

  ASSIST KEY
     (1) in a msg buffer within the first line or at the end of a
         message, the previous undeleted message is displayed;
     (2) in a msg buffer within the first line of an Info cross
         reference, the referent is displayed;
     (3) anywhere else within a msg buffer, the window is scrolled down
         one windowful;
     (4) in a msg summary buffer on a header entry, the message
         corresponding to the header is marked for deletion;
     (5) in a msg summary buffer on or after the last line, all messages
         are marked undeleted.