@SysTech
Thanks again!
You're very welcome.
Those 3D displays are kind of handy for visualizing the radio output but they are right now pretty CPU intensive.
If I may insert yet another suggestion here. While I don't believe you'd gain much by using OpenGL painting for the "waterfall" data, I think switching to it for the 3D displays would work better. I nice side effect would be that you can also render OpenGL from different threads, provided the appropriate locking mechanisms are in place. You could, as the most simple test, try using QOpenGLWidget for those FFT displays.
Kind regards.