In the documentation, it's stated that
Edwin is very similar to GNU Emacs—you should refer to the GNU Emacs manual for information about Edwin's commands and key bindings
So my guess is that you have to:
- First set a mark at the beginning and at the end of the text to be copied:
[Ctrl-spacebar]
- Then copy it:
[Meta-W]
- And to paste back from windows:
[Ctrl-Y]