XForms is a GUI toolkit based on Xlib for X Window Systems. It features a rich set of objects, such as buttons, sliders, and menus etc. integrated into an easy and efficient object/event callback execution model that allows fast and easy construction of X-applications. In addition, the library is extensible and new objects can easily be created and added to the library.
The library is available as 32-bit and 64-bit:
Current version: v1.0.92sp2-1