Upgrading from:

Graphics`ArgColors`

ArgColor, ArgShade, and ColorCircle are obsolete, with simple definitions in terms of system functions.

ArgColor can be defined in terms of Hue, Rescale, and Arg:

Version 5.2 << Graphics`ArgColors` ArgColor[1 + I]

ArgShade can be defined in terms of GrayLevel, Rescale, and Arg:

Version 5.2 ArgShade[1 + I]

ColorCircle can be defined in terms of Hue:

Version 5.2 ColorCircle[6]