GTK-VNC is a VNC viewer widget for GTK+. It is built using coroutines,
allowing it to be completely asynchronous while remaining single threaded.
It supports RFB protocols 3.3 through 3.8 and the VeNCrypt authentication
extension providing SSL/TLS encryption with x509 certificate authentication.
The core library is written in C and a binding for Python using PyGTK is
available. The networking layer supports connections over both IPv4 and IPv6.
Example code illustrates how to build a vncviewer replacement using either C
or Python.

WWW: http://gtk-vnc.sourceforge.net/