libNUI is a hardware accelerated GUI framework that makes it possible to build rich multi-platform applications based on 3D rendered dynamic layouts. Interfaces are built as a composition of widgets and behaviors, and the framework handles positioning, resizing, anchoring, and texture stretching. Objects are connected with synchronous events and delegates for mono-threaded communication, or asynchronous notifications and message queues are used for multi-threaded applications. It also supports strings (including Unicode), paths, files, data streams, fonts, threads, critical sections, audio buffer rendering, and more.
NUI is a GUI ToolKit intended to work with SGI's OpenGL API. It is similar in many ways to GTK+, Qt and even Win32, but with many enhancements in order to make it an easy and yet powerful tool for cross- platform GUI programming. It is currently developed on platforms supported by the NGL framework.