PUBLIC MARKS from nachilau with tag gui

A great docking program

A simple GUI library for OpenGL and DirectX

An simple GUI interface API similiar to Crazy Eddie.

wxAUI is an open-source advanced user interface library that aims to make it easy to implement "cutting-edge" interface usability and design features for wxWidgets applications....

SmartWin Open Source GUI library

Another GUI library called lgi

Crazy Eddie's GUI System is a free library providing windowing and widgets for graphics APIs / engines where such functionality is not natively available, or severely lacking. The library is object orientated, written in C++, and targeted at games developers who should be spending their time creating great games, not building GUI sub-systems!