protected Color getHiBorderColor(int tabIndex) {
        Color backColor = tabPane.getBackgroundAt(tabIndex);
        if (tabIndex == tabPane.getSelectedIndex()) {
            if (backColor instanceof UIResource) {
                return AbstractLookAndFeel.getControlHighlight();
            } else {
                return ColorHelper.brighter(backColor, 40);
            }
        }
        if (tabIndex >= 0 && tabIndex <= tabCount) {
            if (!isTabOpaque() || backColor instanceof UIResource) {
                return AbstractLookAndFeel.getControlHighlight();
            } else {
                return ColorHelper.brighter(backColor, 40);
            }
        }
        return AbstractLookAndFeel.getControlHighlight();
    }