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Unity, even has adopted it for their 2d interface and ubuntu TV. By coding it in Qt you make it native in KDE, and look native in GTK environments since Qt has a gtk theme engine and a clearlooks theme.
You can check the following wiki for some more information
Furthermore you will have the advantage of a single codebase that can work on all of the platforms, which brings home the Java montra code once run everywhere. Unlike java the programs won't have a shitty theme but would look / act more or less native. Plus you gain access to a 2d canvas and a declarite API with Qtquick.