X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/2db38a6f98c2abb42b746064ce97417cccc27e68..c5ad92de10abe251165a21977b388d3e799660ac:/lisp/button.el

diff --git a/lisp/button.el b/lisp/button.el
index 2a9a49c399..0676ba8695 100644
--- a/lisp/button.el
+++ b/lisp/button.el
@@ -1,10 +1,10 @@
 ;;; button.el --- clickable buttons
 ;;
-;; Copyright (C) 2001, 2002, 2003, 2004, 2005,
-;;   2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+;; Copyright (C) 2001-2013 Free Software Foundation, Inc.
 ;;
 ;; Author: Miles Bader <miles@gnu.org>
 ;; Keywords: extensions
+;; Package: emacs
 ;;
 ;; This file is part of GNU Emacs.
 ;;
@@ -37,10 +37,12 @@
 ;; the button is represented by a marker or buffer-position pointing
 ;; somewhere in the button.  In the latter case, no markers into the
 ;; buffer are retained, which is important for speed if there are are
-;; extremely large numbers of buttons.
+;; extremely large numbers of buttons.  Note however that if there is
+;; an existing face text-property at the site of the button, the
+;; button face may not be visible.  Using overlays avoids this.
 ;;
 ;; Using `define-button-type' to define default properties for buttons
-;; is not necessary, but it is is encouraged, since doing so makes the
+;; is not necessary, but it is encouraged, since doing so makes the
 ;; resulting code clearer and more efficient.
 ;;
 
@@ -52,10 +54,7 @@
 ;; Use color for the MS-DOS port because it doesn't support underline.
 ;; FIXME if MS-DOS correctly answers the (supports) question, it need
 ;; no longer be a special case.
-(defface button '((((type pc) (class color))
-		   (:foreground "lightblue"))
-		  (((supports :underline t)) :underline t)
-		  (t (:foreground "lightblue")))
+(defface button '((t :inherit link))
   "Default face used for buttons."
   :group 'basic-faces)
 
@@ -289,9 +288,12 @@ button-type from which to inherit other properties; see
 `define-button-type'.
 
 This function is like `make-button', except that the button is actually
-part of the text instead of being a property of the buffer.  Creating
-large numbers of buttons can also be somewhat faster using
-`make-text-button'.
+part of the text instead of being a property of the buffer.  That is,
+this function uses text properties, the other uses overlays.
+Creating large numbers of buttons can also be somewhat faster
+using `make-text-button'.  Note, however, that if there is an existing
+face property at the site of the button, the button face may not be visible.
+You may want to use `make-button' in that case.
 
 BEG can also be a string, in which case it is made into a button.
 
@@ -347,7 +349,9 @@ Also see `make-text-button'."
 ;; Finding buttons in a buffer
 
 (defun button-at (pos)
-  "Return the button at position POS in the current buffer, or nil."
+  "Return the button at position POS in the current buffer, or nil.
+If the button at POS is a text property button, the return value
+is a marker pointing to POS."
   (let ((button (get-char-property pos 'button)))
     (if (or (overlayp button) (null button))
 	button
@@ -476,5 +480,4 @@ Returns the button found."
 
 (provide 'button)
 
-;; arch-tag: 5f2c7627-413b-4097-b282-630f89d9c5e9
 ;;; button.el ends here