Qt™ is a C++-based class library to build user interfaces. It also includes many utility classes like string classes and classes to handle input and output. It provides most of the widgets you will see in a KDE application: menus, buttons, sliders, etc.. Qt™ is a cross-platform library that allows you to write code that will compile on UNIX® systems as well as Windows® and embedded devices. You can learn more about Qt™ at http://www.trolltech.com.

Qt™ is a very sophisticated toolkit that provides everything that is needed to build a modern user interface. Qt™ is written in C++, thus allowing object-oriented development which ensures efficiency and code reuse in a project the size and scope of KDE. In our opinion there is no better toolkit available for UNIX® systems and that it would have been a grave mistake to try to build KDE on anything but the best.

There are a number of toolkits available. To provide a consistent user interface and to keep used resources such as memory to a minimum, KDE can use only one of them. Qt™ was selected for the reasons mentioned above.

It is! As of September 4, 2000, version 2.2 of the Qt™ libraries were licensed under the GPL, thereby fulfiling all aspects of “free software”.

You can use the KDE libraries to write “commercial and closed source” as well as “commercial and open source” software. If you write open source software you can use the Qt™ free edition. But if you write closed source software you may not use the Qt™ free edition; you need to obtain the Qt™ professional edition from Troll Tech.

If you want more information, please contact Troll Tech directly.