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.
ROOT is an OO framework for large-scale scientific data analysis and data mining. It contains an efficient hierarchical OO database, a C++ interpreter, advanced statistical analysis, visualization, introspection, documentation, networking, and GUI classes. The command/scripting language is C++, and large scripts can be compiled and dynamically linked in. Using the PROOF (Parallel ROOT Facility) extension, large databases can be analyzed in parallel. The system runs on all known POSIX platforms, Windows, and MacOS X.
The Date::Calc package consists of a (pure-Perl) wrapper which either loads Date::Calc::XS (a separate implementation in C and XS) or Date::Calc::PP (a pure-Perl implementation which is part of the Date::Calc package). The Date::Calc::XS and Date::Calc::PP modules perform all kinds of date calculations based on the Gregorian calendar (the one used in all Western countries today), according to relevant norms and standards: ISO/R 2015-1971, DIN 1355 and, to some extent, ISO 8601 (where applicable). The package is designed as an efficient toolbox, not a bulky ready-made application. It provides extensive documentation and examples of use, multi-language support, and special functions for business needs.
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.
wxWidgets is a cross-platform C++ GUI library, offering classes for all common GUI controls as well as a comprehensive set of helper classes for most common application tasks, ranging from networking to HTML display and image manipulation. wxWidgets uses native widgets on all platforms whenever possible and fills missing gaps on some platforms using generic controls written with wxWidgets itself.
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.
lcc is a retargetable compiler for ISO Standard C. It generates code for the ALPHA, SPARC, MIPS R3000, and Intel x86 and its successors. Despite the fact that any Linux system will already have gcc, there are reasons for installing lcc as well. lcc is small, compiles more quickly than gcc, and helps prevent some porting bugs. It also gives more useful error messages in some circumstances. This means that it is sensible to use lcc during development, and gcc for the final binary where you want the better optimization.