DLDialog offers the capability to draw a variety of widgets, in order to ease the human user in feeding input to the script. The program is designed to be particularly useful to implement system administration scripts. It includes a definition language similar to Tcl/Tk. It can display dialogs (with the same definition) using characters with the tvision/ncurses interface or using graphical windows with the QT/X11 interface.
FOX is a C++-based toolkit for GUI development. It includes a rich set of widgets and has powerful yet simple layout managers, MDI widgets, and mega-widgets. FOX incorporates support for XDND for drag and drop, X clipboard and X Selection, watching other I/O channels and sockets, timers and idle processing, object serialization and deserialization, a registry to save persistent settings, and 3D widgets using Mesa or OpenGL. FOX works on Linux, IRIX, Solaris, HP/UX, AIX, Tru64 Unix, Windows 9x,NT,2K (VC++, GNUWIN32, Borland, VisualAge C++), FreeBSD, and Sequent.
Xclasses is a C layout library for the X Window System. All objects (called gadgets) are font sensitive, i.e. their size changes with the size of the used screen font and the size of the window. All this is done by Xclasses itself. The user may choose any kind of font style and size.
gtkmm (previously known as Gtk--) is a C++ interface for the popular GUI library GTK+. It provides a convenient interface for C++ programmers to create graphical user interfaces with GTK+'s framework. Highlights include typesafe callbacks, widgets which are extensible by inheritance, and many classes that can be easily combined to quickly create complex user interfaces.
FLTK (pronounced "fulltick") is a cross-platform C++ GUI toolkit for UNIX/Linux (X11), Microsoft Windows, and Mac OS X. It provides modern GUI functionality without the bloat, and supports 3D graphics via OpenGL and its built-in GLUT emulation. FLTK is designed to be small and modular enough to be statically linked, and also works fine as a shared library. It also includes an excellent UI builder called FLUID that can be used to create applications in minutes.
JX is a full-featured C++ application framework and GUI widget library for use with the X Window System. It provides support for all facets of application development, including distributed applications, and aims to combine the best of MacOS and NeXTSTEP. It is built directly on top of Xlib and has been carefully optimized for performance.
XForms is a GUI toolkit based on Xlib. It comes with a rich set of objects such as buttons, browsers, sliders, and menus integrated into an elegant event/object callback execution model that allows for fast and easy construction of X applications. In addition, the library supports loading and writing images, format conversion, and simple image processing. It consists of a flexible set of C-routines that can be used in C and C++ programs, is efficient and portable, and runs on all major Unix platforms and OpenVMS, OS/2, and Windows NT.