If the user provides an ssh public key file that doesn't contain compatible contents, then the user gets the generic "The specified key cannot be loaded". It would be much more helpful if the user is informed that the file is incompatible with ThinLinc. Ideally, also why, if it's a common type of incompatibility (e.g. specifying the public key instead of the private). This is a continuation of bug 7313, where a bug in OpenSSL prevented us from properly solving this issue.