I don't know about the reason for the message as I don't use WINE, but you can always use an external editor. There isn't a setting in mIRC. All you do is open the file in any text editor, make changes, and save it. You will need to either make the changes while mIRC is closed or else reload the script after making the changes so they start working in mIRC. mIRC won't automatically see your changes if you change the file outside of mIRC while mIRC is running.
