Using subdomains. for the middle class. use it like using a browser. for file transfers, FTP/FTPS might be able to use winbuilder because it already supports tcp. I think for CuteFTP similar to SmartFTP(I've been using this feature for a long time). WindowsSCP says it can handle this, but I think it's already in winbuilder.
EdtFTPj, makes me think that this crossplatform data is implemented. winbuilder can use the java platform, as well as can use it. How about scripting EdtFTPj?