I wrote:
>
> Another thing field setters would do is mean that gdk-color-change can
> take the same parameters as the C gdk_color_change, ie. a GdkColor
> containing a pixel value.  Unnecessary variations between the C and
> Scheme functions are not good.

I propose to make this change,

        * gdk-1.2.defs (gdk_color_change): Remove separate pixel parameter,
        take scheme-level parameters the same as the C function.
        * gdk-support.c (gdk_color_change_interp): Remove.

Whether a GdkColor structure is a particularly good way to pass
pixel+r+g+b is a matter for debate, personally I think it's sensible
enough in the context of colormap tricks.  Either way if there's a
burning need for some other interface then it should be under a new
name to avoid any possible confusion.