Added support for alpha in rectangle drawing shapes - including margins and background.  This is not perfect because it doesn't support 0 alpha.  Lowest is 1.  Need to look into how Android works for this.  Since numbers are argb, colors represented in rbg would always have 0 alpha - which is clearly not the intent.  Ideally the alpha byte should work in reverse to that 0 indicates ff and ff indicate 0.  But I don't want to rock the boat.  For now just set alpha = 1 if you want lowest possible.