Color inactiveColor

The color that should be used in the inactive state (i.e., when value is false).

For example, a checkbox should use this color when unchecked.

Source 

Color get inactiveColor => _inactiveColor;
void inactiveColor=(Color value)

Source 

set inactiveColor(Color value) {
  assert(value != null);
  if (value == _inactiveColor)
    return;
  _inactiveColor = value;
  markNeedsPaint();
}