indicatorWeight property
final
The thickness of the line that appears below the selected tab.
The value of this parameter must be greater than zero.
If ThemeData.useMaterial3 is true and TabBar is used to create a primary tab bar, the default value is 3.0. If the provided value is less than 3.0, the default value is used.
If ThemeData.useMaterial3 is true and TabBar.secondary is used to create a secondary tab bar, the default value is 2.0.
If ThemeData.useMaterial3 is false, the default value is 2.0.
If indicator is specified or provided from TabBarThemeData, this property is ignored.
Implementation
final double indicatorWeight;