hover = live readout (snaps to real data samples — never interpolated; Smith design paths read out too)
click = pin marker
scroll = zoom at cursor
drag = pan on Smith · box-zoom on XY (⇧drag pans)
double-click = reset zoom
legend: drag moves · click entry hides · double-click resets · ○ start ● end on Smith
color = S-parameter · line style = file · matrix cell cycles – / L / R axis