Klaus,
Thank you so much for adding this feature!
This is making editing so much nicer - now when I edit code in a button, it opens in my preferred editor and I can see syntax highlighting etc - very nice. and cut and paste buffers work better with other programs also.

One suggestion for a tweak - I suspect that the file name you pass to the editor either does not have an extension or is something other than .m1s.  Many editors select language highlights etc based on extension. In my editor, the passed file opens as plain text, so I figure it was .txt or no extension that was passed.

Would you set the extension of the passed temp file to .m1s?

Dave