private void fillRect( Graphics g, Color color, int x, int y, int width, int height ) {
			// fill white if color is translucent
			if( color.getAlpha() != 255 ) {
				g.setColor( Color.white );
				g.fillRect( x, y, width, height );
			}

			g.setColor( color );
			g.fillRect( x, y, width, height );
		}
Creates a UI defaults inspector panel that can be embedded into any window.
flatlaf-extras/src/main/java/com/formdev/flatlaf/extras/FlatUIDefaultsInspector.java