`face' widget type

[Richard Stallman]

I got rid of the confusing double-levels of hiding,
and the double magic button, by redefining `face'
in terms of `editable-field'.  I also put in a "sample"
to show what the chosen face looks like.

It works except for one thing: when I set a different face name,
the sample does not update.  How can I make it update?