[SSmutz]

*.nw can and can't be openned, depending on how you got them.
If you save a *.nw file using Crtl+5 (or whatever it is), it saves the level in *.graal format, only renamed. And you can open it in the editor.
If you get a *.nw level straight from the ftp, you can't open it, unless you have a developer version of Graal (which very few people have).
I know this because, I've saved and opened files from online mode. And when I had my harddrive reformatted, I lost the bomy cavern files and Stefan had to download them from the ftp and send them to me, and he sent me a "developer version" (thats what he called it) of Graal, cuz I wasn't able to open the cavern files with my usual Graal.