This is a GUI toolkit that I had never heard of or seen until yesterday.
Notus is a GUI toolkit based on the ideas of generic C++ programming, according to the website it is an attempt to create a domain model.
It hasn't been developed for a very long time now (over a year) according to the website but looking at the CVS logs there were changes six months ago to the source code.
It is by no means a finished article but it has some interesting ideas (although it looks like it could e incredibly complicated thanks to lots of templates). It is not as comprehensive as the other library that uses the same concepts Win32 GUI Generics.
The demos are quite simple and a few years out of date, but it seems to at least work. It is a shame that none of the Boost-ified GUI libraries seem to have caught on, or at least been carried on.