When connecting after specifying an empty path for the public key file in the ThinLinc client you get a confusing error message: "Server does not support any of the chosen authentication methods."
The message only show on Windows. On Linux you get the message "The specified key doesn't exist, or has been moved. Please check the file path and try again."
Works on Linux and Windows.
Looks good. Verified on Windows 10, Fedora 30 and macOS 10.14.