Yes, there is an open source editor, freebxmlbp, which was developed at Middle East Technical University (METU). The tool is under development with an initial user's guide recently circulated; the tool is available at: http://sourceforge.net/projects/freebxmlbp (http://sourceforge.net/cvs/?group_id=154705).