[Emacs-diffs] emacs-26 73508e6: Improve documentation of face numbers

[Eli Zaretskii]

branch: emacs-26
commit 73508e62459113be4c7c101648afbe541dd18558
Author: Eli Zaretskii <address@hidden>
Commit: Eli Zaretskii <address@hidden>

    Improve documentation of face numbers
    
    * doc/lispref/display.texi (Face Functions): Mention where the
    face number is used and that it depends on the 'face' property
    of the face symbol.  Improve indexing.
---
 doc/lispref/display.texi | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index b3ce7fb..921d58a 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -3038,10 +3038,17 @@ value, which inherits from @var{face}'s global 
definition.
 This function returns a list of all defined face names.
 @end defun
 
address@hidden face number
address@hidden face property of face symbols
 @defun face-id face
 This function returns the @dfn{face number} of face @var{face}.  This
 is a number that uniquely identifies a face at low levels within
 Emacs.  It is seldom necessary to refer to a face by its face number.
+However, functions that manipulate glyphs, such as
address@hidden and @code{glyph-face} (@pxref{Glyphs}) access
+the face numbers internally.  Note that the face number is stored as
+the value of the @code{face} property of the face symbol, so we
+recommend not to set that property of a face to any value of your own.
 @end defun
 
 @defun face-documentation face