Subject: Re: 23.1; face doc unclear - no explanation of "underlying" face or attribute value

From: Chong Yidong <[email-masked]>
Date: Sat, 15 Aug 2009 17:15:52 -0400

> In (elisp)Face Attributes, things are explained in terms of
> "underlying" face. But this notion is never introduced or explained.

Thanks, I've tweaked the text and added a reference to the node
Displaying Faces, where the concept is explained.

> I have no idea what was intended in any of these passages.

Here's an experiment that should make this clear.  Go to the default
*scratch* buffer and evaluate the following lines, one at a time:

;; Give the comments in this buffer a height of 15.
(set-face-attribute 'font-lock-comment-face nil :height 150)
;; Give characters 5 to 8 a height that's 0.9 times that of the
;; underlying face, in this case font-lock-comment-face.
(setq ov (make-overlay 5 8))
(overlay-put ov 'face (list :height 0.9))