• Written in C, can be used in both C and C++.
• Available On most UNIX and other platforms with XLib installed, meaning NT and PowerPC.
• Has Forms designer, which will interactively generate C code to create forms user specifies.
• Can create custom forms.
• Doesn't look as sleek as the other two.
• Doesn't support Multithreading
• Has GUI Builder
• OpenGL Support

Buttons:

Boxes & Frames:

Scrollbars, Counters, Sliders & Dials:

Input Fields, Pop up messages & Menus:

Tabs and other Miscellaneous things: