I got fldigi to decode signals received by quisk. Check the Quisk and Fldigi exercise for details.
I could not find a way to control the quisk frequency setting from fldigi. So while this combination works it is largely a novelty. It is fun to play with, decoding signals, examining the effect of quisk filters, and such, but real operating will have to wait until there is a rig interface connection between the two.
That's really too bad, because I like the way quisk works with the http://www.wb5rvz.com/sdr/ensemble_rx_ii/Softrock Ensemble receivers, particularly the way it avoids changing the Si570 oscillator frequency when simply selecting a signal from the waterfall.