Simply an additional mode in which the back layer in the analyzer is filled, but the the front layer only is curve/outline drawn. I think this would quite a lot improve readability. The front layer however sould be drawn more fatty, and maybe be red always?
I don’t think colors of the tracks / the rainbow make a lot of sense in outline drawing mode at all… Especially when using retina / hidpi, it is then often barely visible at all.
So an option “fatten and redden the outline mode”, too.
What about a “monochromic” drawing in this combined mode, background layer is filled with track color, and the front layer is invert-masked on top, so black on the background layer, but the same color on black? And then quite fat?
btw. happy Easter! 
