Some cleanup and 'n' button to center the waveform around 0
Drawing on fft works (and produces broader range of sounds than drawing on time waveform), but drawing phase will probably require more effort.
Better frequency drawing.  Can make some really cool sounds with frequency drawing, need a save capability.
Can now draw phase.

TBD probably want logarithmic spectrum in the x-axis, more mouse fidelity to change values lower down in frequency.
playing with phase unwrapping