See http://mail.gnome.org/archives/balsa-list/2002-January/msg00295.html

The following patch allows the user to specify the title for the message
window, specifying whether to include any of:
 - the `From:' header;
 - the `From:' mailbox;
 - the subject.

Files:

 * help/C/balsa.sgml: documentation.

 * libbalsa/message.[hc]: new function
     gchar *libbalsa_message_title (LibBalsaMessage * message,
                                    const gchar * format);
     which makes up a title string for the message in the given format.

 * libbalsa/misc.[hc]: new function
     gchar *libbalsa_truncate_string(const gchar * str,
                                     gint length, gint dots);
     which truncates the string to at most length, and replaces the last 
     dots characters with '.' if the string was truncated.

 * src/balsa-app.h: new member balsa_app.message_title_format.

 * src/pref-manager.c: user interface to balsa_app.message_title_format.

 * src/save-restore.c: save and restore balsa_app.message_title_format.

 * src/message-window.c: use the new libbalsa_message_title()