(invert-face): Check for 'unspecified, not for nil,

when testing whether face colors are not specified.  From
David.Kastrup@t-online.de (David Kastrup).

diff --git a/lisp/faces.el b/lisp/faces.el
index bb9d4471da341dabcb7d9590ec865029105976f9..ac9b6645ae068e4b75a54aff9e494bad2623e7ce 100644 (file)
--- a/lisp/faces.el
+++ b/lisp/faces.el
@@ -824,14 +824,14 @@ Use `set-face-attribute' or `modify-face' for finer control."
 
 (defun invert-face (face &optional frame)
   "Swap the foreground and background colors of FACE.
-FRAME nil or not specified means change face on all frames.
+If FRAME is omitted or nil, it means change face on all frames.
 If FACE specifies neither foreground nor background color,
 set its foreground and background to the background and foreground
 of the default face.  Value is FACE."
   (interactive (list (read-face-name "Invert face ")))
   (let ((fg (face-attribute face :foreground frame))
        (bg (face-attribute face :background frame)))
-    (if (or fg bg)
+    (if (not (and (eq fg 'unspecified) (eq bg 'unspecified)))
        (set-face-attribute face frame :foreground bg :background fg)
       (set-face-attribute face frame
                          :foreground