[Emacs-diffs] emacs-25 3ef86fd: Clarify documentation of face attribute functions

[Eli Zaretskii]

branch: emacs-25
commit 3ef86fd06378f43f8d90c7c120b4fe605d187e9f
Author: Eli Zaretskii <address@hidden>
Commit: Eli Zaretskii <address@hidden>

    Clarify documentation of face attribute functions
    
    * doc/lispref/display.texi (Attribute Functions): Make sure to
    document that an omitted FRAME argument means the same as nil.
    (Bug#24879)
---
 doc/lispref/display.texi |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 2e316f8..f94628c 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -2548,7 +2548,7 @@ modifying the attributes of a named face.
 This function returns the value of the @var{attribute} attribute for
 @var{face} on @var{frame}.
 
-If @var{frame} is @code{nil}, that means the selected frame
+If @var{frame} is omitted or @code{nil}, that means the selected frame
 (@pxref{Input Focus}).  If @var{frame} is @code{t}, this function
 returns the value of the specified attribute for newly-created frames
 (this is normally @code{unspecified}, unless you have specified some
@@ -2644,8 +2644,8 @@ created frames.
 
   The following commands and functions mostly provide compatibility
 with old versions of Emacs.  They work by calling
address@hidden  Values of @code{t} and @code{nil} for
-their @var{frame} argument are handled just like
address@hidden  Values of @code{t} and @code{nil} (or
+omitted) for their @var{frame} argument are handled just like
 @code{set-face-attribute} and @code{face-attribute}.  The commands
 read their arguments using the minibuffer, if called interactively.
 
@@ -2714,7 +2714,8 @@ name used for @var{character}.
 @defun face-foreground face &optional frame inherit
 @defunx face-background face &optional frame inherit
 These functions return the foreground color (or background color,
-respectively) of face @var{face}, as a string.
+respectively) of face @var{face}, as a string.  If the color is
+unspecified, they return @code{nil}.
 @end defun
 
 @defun face-stipple face &optional frame inherit