emacs-27 79f381b: One more improvement of left/right-fringe display spec docs

[Eli Zaretskii]

branch: emacs-27
commit 79f381b4a6675b007113682e2d4245e2448d637f
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    One more improvement of left/right-fringe display spec docs
    
    * doc/lispref/display.texi (Fringe Bitmaps): Yet another
    clarification of how to use FACE in left/right-fringe display
    spec.
---
 doc/lispref/display.texi | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index ecb9cff..2ef27c0 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -4282,7 +4282,11 @@ background colors are to be used to display the bitmap, 
using the
 attributes of the @code{fringe} face for colors that @var{face} didn't
 specify.  If @var{face} is omitted, that means to use the attributes
 of the @code{default} face for the colors which the @code{fringe} face
-didn't specify.
+didn't specify.  For predictable results that don't depend on the
+attributes of the @code{default} and @code{fringe} faces, we recommend
+you never omit @var{face}, but always provide a specific face.  In
+particular, if you want the bitmap to be always displayed in the
+@code{fringe} face, use @code{fringe} as @var{face}.
 
   For instance, to display an arrow in the left fringe, using the
 @code{warning} face, you could say something like: