PRUint32 NS_GetLuminosity(nscolor aColor)
PRInt32 NS_GetLuminosity(nscolor aColor)
PRUint32 NS_GetLuminosity(nscolor aColor){  return (NS_GET_R(aColor) * RED_LUMINOSITY +          NS_GET_G(aColor) * GREEN_LUMINOSITY +          NS_GET_B(aColor) * BLUE_LUMINOSITY);}