overlayColor property
final
The color for the checkbox's Material.
Resolves in the following states:
If null, then the value of activeColor with alpha kRadialReactionAlpha and hoverColor is used in the pressed and hovered state. If that is also null, the value of CheckboxThemeData.overlayColor is used. If that is also null, then the default value is used in the pressed and hovered state.
Implementation
final MaterialStateProperty<Color?>? overlayColor;