Experimental code at present!
http://cvs.eurostep.com/bugs/show_bug.cgi?id=843#c5
http://cvs.eurostep.com/bugs/show_bug.cgi?id=850#c2
no message
http://cvs.eurostep.com/bugs/show_bug.cgi?id=850#c1
http://cvs.eurostep.com/bugs/show_bug.cgi?id=849#c2
http://cvs.eurostep.com/bugs/show_bug.cgi?id=849#c1
http://cvs.eurostep.com/bugs/show_bug.cgi?id=848#c2
http://cvs.eurostep.com/bugs/show_bug.cgi?id=848#c1