Qt Quick is a component of the Qt C++ graphical user interface library, which consist of three parts:
- Qt Quick C++ classes, such as QDeclarativeContext for setting properties in the QML view
- QML support in Qt Creator, which is a cross platform, integrated development environment for Qt programming
While the QML package comes with several built-in elements, they often are too generic for specific needs. In order to fulfil this need, Nokia released Qt Quick Components package for Symbian and MeeGo Harmattan. These reduce the time to implement an application on those platforms by adding native look and feel in the reach of QML.
While those two packages serve their purpose on the given platforms, there is still a need for other platforms like the desktop environment for example. Now since Qt 5 will promote primarily to use QML for the user interface while C++ will do all the heavy processing in the background, there will be increasing demand for UI components.
Nokia has been working on Desktop components for a while now and just made another post in the Qt Labs Blog.
A quick Google search reveals that others are making their components too, like it should be. Few examples:
In case you are using Qt in your application and plan to make release in the future, you should start migrating to Qt 5 and Qt Quick now. Why not make a set of components of your own. KDE is porting.