private static ColorUIResource parseColorOver( List<String> params, Function<String, String> resolver )
		throws IllegalArgumentException
	{
		String foregroundStr = params.get( 0 );
		String backgroundStr = params.get( 1 );

		// parse foreground color
		ColorUIResource foreground = (ColorUIResource) parseColorOrFunction( resolver.apply( foregroundStr ), resolver );
		if( foreground == null || foreground.getAlpha() == 255 )
			return foreground;

		// foreground color without alpha
		ColorUIResource foreground2 = new ColorUIResource( foreground.getRGB() );

		// parse background color
		ColorUIResource background = (ColorUIResource) parseColorOrFunction( resolver.apply( backgroundStr ), resolver );
		if( background == null )
			return foreground2;

		// create new color
		float weight = foreground.getAlpha() / 255f;
		return new ColorUIResource( ColorFunctions.mix( foreground2, background, weight ) );
	}
Syntax: over(foreground,background)
  - foreground: a foreground color (e.g. #f00) or a color function;
                the alpha of this color is used as weight to mix the two colors
  - background: a background color (e.g. #f00) or a color function
flatlaf-core/src/main/java/com/formdev/flatlaf/UIDefaultsLoader.java