About Color Lists  An NSColorList is an ordered list of NSColor
objects, identified by keys. Instances of NSColorList, or more
simply, color lists, are used to manage named lists of color
objects. The list-mode color picker of an NSColorPanel object
uses instances of NSColorList to represent any lists of colors
that come with the system, as well as any lists created by the
user. An application can use NSColorList to manage document-
specific color lists, which may be added to an application’s
NSColorPanel object using its attachColorList: method.  An
NSColorList object is similar to a dictionary object: A color
object is added to, looked up in, and removed from the list by
specifying its key, which is a string object. These keys are
used to identify the colors in the list and are used to display
the color to the user in the color panel. In addition, colors
can be inserted at specified positions in the list.  The color
list has a name, specified when you create the object using
either the initWithName: or initW