@Override
	protected void paintHorizontalLine( Graphics g, JComponent c, int y, int left, int right ) {
		((Graphics2D)g).fill( new Rectangle2D.Float( left, y, right - left, UIScale.scale( 1f ) ) );
	}
Similar to super.paintRow(), but supports wide selection and uses
inactive selection background/foreground if tree is not focused.
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTreeUI.java