BottomAppBar: surfaceTintColor doc should say it only applies in Material 3 #124536
Description
Here's the full doc on BottomAppBar.surfaceTintColor currently:
/// The color used as an overlay on [color] to indicate elevation.
///
/// If this is null, no overlay will be applied. Otherwise the
/// color will be composited on top of [color] with an opacity related
/// to [elevation] and used to paint the background of the [BottomAppBar].
///
/// The default is null.
///
/// See [Material.surfaceTintColor] for more details on how this overlay is applied.
final Color? surfaceTintColor;It's very easy to confuse the Material 3 "surface tint" effect with the Material 2 "overlay" effect, but they are different. (See ElevationOverlay.applySurfaceTint and ElevationOverlay.applyOverlay.)
"Surface tint" isn't and shouldn't be applied when ThemeData.useMaterial3 is false. The linked Material.surfaceTintColor doc makes that clear, but I think it would help if BottomAppBar's doc mentioned it too. Perhaps with something like:
/// A custom color for the Material 3 surface-tint elevation effect.
///
/// In Material 3, a "surface tint" with an opacity related to [elevation]
/// will be applied to the [BottomAppBar]'s background.
/// Use this property to override the default color of that tint.
///
/// If this property is null, then [BottomAppBarTheme.surfaceTintColor]
/// of [ThemeData.bottomAppBarTheme] is used.
/// If that is also null, [ColorScheme.surfaceTint] is used.
///
/// Ignored if [ThemeData.useMaterial3] is false.
///
/// The default is null.
///
/// See [Material.surfaceTintColor] for more details on how this overlay is applied.
final Color? surfaceTintColor;