The book covers version Qt version 3, as this is the current version (version 4 is on its way and should be available Q2 2005).

Qt has an extensible set of widgets, covering all the current display needs. Qt has been used as a fundation by KDE.

The documentation is excellent, although most of the time it is not needed, as the programming model is one of the most consistent I have ever seen (among Amiga, WinProc, Mac toolbox, MFC and GTK+), so you don't need to search for a particular method name, you KNOW what it is!

Qt is available as a dual-license product : either GPL for a non-commercial use, or with a per seat license for commercial use. Note that the GPL version is not a restricted version.

And last but not least, Qt also has a Qt/Embedded version, suitable for small footprint embedded targets with frame buffer support.

Something that is not well-documented (the link is hidden in the Windows system specific Notes in the version 3 documentation !!!), is that it is possible to customize very deeply the features that are integrated, dropping all unnecessary bloat and thus reducing compile time.