Portals; page.UploadFiles method not working when running from within finPOWER Connect

The page.UploadFiles (or widget.UploadFiles) method was not working when a Portal was being run from within finPOWER Connect desktop.

For example, the sample "Client Connect" Portal allows a file to be uploaded when creating a new message on the Messages page. This was working fine when the Portal was run from Web Services but was doing nothing (not even adding the new message) when run from within finPOWER Connect.