protected void paintSeparator( Graphics g ) {
			if( first && !selected ) {
				g.setColor( FlatLaf.isLafDark() ? Color.gray : Color.lightGray );
				g.fillRect( 0, 0, getWidth() - 1, 1 );
			}
		}
Creates a UI defaults inspector panel that can be embedded into any window.
flatlaf-extras/src/main/java/com/formdev/flatlaf/extras/FlatUIDefaultsInspector.java