bug#15427: 24.3.50; `customize-face' in Customize, show `Background' attribute using background

[Drew Adams]

FWIW, I agree about the widget and custom code.
And it's doc is not super helpful.

(defun widget-color-sample-face-get (widget)
  (let* ((value (condition-case nil
                    (widget-value widget)
                  (error (widget-get widget :value)))))
    (if (color-defined-p value)
        (list (cons 'background-color value))
      'default)))

But I think, as said in the enhancement
request, that it's good to show the
effect of the color BOTH as a foreground
and as a background.