message: color smoothing for element-index theme
diff: @@ -64,6 +64,7 @@ export function ElementIndexColorTheme(ctx: ThemeDataContext, props: PD.Values<E
  return {
  factory: ElementIndexColorTheme,
  granularity: 'groupInstance',
  + preferSmoothing: true,
  color,
  props,
  description: Description,
  