The foreground color for widgets (knobs, text, overscroll edge effect, etc).
Accent color is also known as the secondary color.
The theme's colorScheme property contains ColorScheme.secondary, as well as a color that contrasts well with the secondary color called ColorScheme.onSecondary. It might be simpler to just configure an app's visuals in terms of the theme's colorScheme.
final Color accentColor