Following my success with integrating the frequency control widget from cutesdr into gqrx I have decided to try the same with the FFT plot and waterfall widget. This too seemed to be a single C++ class that might be easy to integrate into my experimental software receiver powered by GNU Radio and Qt GUI.
It looks like Moe Wheatley, AE4JY, is working on a cross platform software defined radio receiver intended for SDR hardware from RFSPACE. It is written using the Qt toolkit and will be available soon under an open source license with the purpose of providing an SDR interface program example for other developers. It is still very early and no code has been released yet, but you can watch this first demo video published few days ago and you can also join the CuteSDR Yahoo group if you are interested in following the project.