To open an M4 file in M3

Just a thought. While the experts are addressing some of the glitches in M4 you may want to open your unfinished M4 file in M3 to complete it. The obvious way doesn't work, and cutting and pasting doesn't work. But if you export your M4 file as an .xml file, M3 will recognise it and open it, allowing you to save it as an M3 file.