Qt5.5.0 / 5.6.0 Alpha
Qt is an open source project that works as a cross-platform SDK (Software Development Kit) and GUI toolkit with APIs for C++ programming. It is a cross-platform framework, supporting the Linux, Microsoft Windows and Mac OS X operating systems.
When installing the program in a Linux-based operating system, it will provide users with several command-line and graphical utilities that can be used to configure the look and feel of Qt applications, as well as to compile Qt programs or choose the default version to use, if multiple ones are installed.
The Qt Creator
While Qt Creator comes with UI designer tools and on-device debugging functionality, the included tools and toolchains provide Qt developers with everything they need, from simulators and local or remote compilers, to internationalization support and device toolchains.
The Qt Configuration
A graphical application called Qt Configuration will allow users to select how the Qt application will blend in the current desktop environment. For example, you can use Qt apps in the GNOME desktop environment and they will look the same as existing GTK+ apps.
In addition, you can also choose a default font, enable GUI effects, modify feel and global strut settings, as well as to configure the Phonon multimedia framework component (if available).
The Qt UI creation toolkit will allow users to create rich, touch-enabled graphical user interfaces and applications in a timely manner. It aims to combine the Qt framework with tools designed for the creation of applications for Symbian phones and the Nokia N9 smartphone.
Summing up, Qt is a strong rival to existing open source GUI toolkits, such as the highly acclaimed GTK+ project. It provides some unique features, compatibility with other GUI styles, as well as platform independence.