Earlier versions of the Windows ThinLinc Client (4.0.0 and earlier) could be used in conjunction with the Putty Pageant authentication agent. Since we switched to OpenSSH in 4.1.0, this no longer works. We could consider supporting Pageant even OpenSSH. Note that ssh-agent (for Linux etc) also does not work; that's bug 4534.
See also: https://github.com/cuviper/ssh-pageant https://github.com/wesleyd/charade