anchor.diff:  
       ThemeData themeData = Theme.of(context);
       Color backgroundColor = Material.of(context).color;
  -    Color indicatorColor = themeData.indicatorColor;
  +    Color indicatorColor = config.indicatorColor ?? themeData.indicatorColor;
       if (indicatorColor == backgroundColor) {
         // ThemeData tries to avoid this by having indicatorColor avoid being the
         // primaryColor. However, it's possible that the tab bar is on a
  
positive.code: 
      final TextStyle textStyle = themeData.primaryTextTheme.body2;
      final IconThemeData iconTheme = themeData.primaryIconTheme;
      final Color textColor = themeData.primaryTextTheme.body2.color.withAlpha(0xB2); // 70% alpha
  
      List<Widget> tabs = <Widget>[];
      bool textAndIcons = false;
      int tabIndex = 0;
      for (TabLabel label in config.labels.values) {
        tabs.add(_toTab(label, tabIndex++, textColor, indicatorColor));
        if (label.text != null && (label.icon != null || label.iconBuilder != null))
          textAndIcons = true;
      }
  
negative.code:   TabBar({
      Key key,
      this.labels,
      this.isScrollable: false,
      this.indicatorColor,
      this.labelColor
    }) : super(key: key, scrollDirection: Axis.horizontal);
  
    /// The labels to display in the tabs.
  