Xnb: X protocol libraries for C#/.NET
The X protocol .NET Binding (Xnb)  is a C# implementation of XCB, a replacement for Xlib featuring a small footprint, latency hiding, direct access to the protocol, improved threading support, and extensibility.
In addition to the protocol transport layer and full coverage of all current Xorg extensions, Xnb also provides a basic implementation of the Xau library and xauth tool for managing X authentication.
Xnb has not yet reached a usable state.
It can currently be found in Mono svn but is is due to be maintained in the NDesk git repository.