NAME
        ChangeToSelectedIconColor -- Modify an RGB colour value for use in
            a selected icon image (V44)

   SYNOPSIS
        ChangeToSelectedIconColor(cr)
                                  A0

        VOID ChangeToSelectedIconColor(struct colorregister *cr);

   FUNCTION
        This function will change the provided RGB colour value to make it
        suitable for use in an icon's select image. This may involve darkening
        or toning the colour. Usually, icon.library calls this function
        when creating a select image for palette mapped icons which do not
        contain "real" select images.

   INPUTS
        cr -- Pointer to a colorregister, containing the rgb colour value
            to be changed.