@Override
	protected void paintFocusIndicator( Graphics g, int tabPlacement, Rectangle[] rects, int tabIndex,
		Rectangle iconRect, Rectangle textRect, boolean isSelected )
	{
	}
Actually does nearly the same as super.paintContentBorder() but
  - not using UIManager.getColor("TabbedPane.contentAreaColor") to be GUI builder friendly
  - tabsOverlapBorder is always true
  - paint full border (if enabled)
  - not invoking paintContentBorder*Edge() methods
  - repaint selection
  - painting active tab border style
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTabbedPaneUI.java