Handle `(space ...)' display spec as paragraph separator.

 src/xdisp.c (compute_display_string_pos): Return 2 in DISP_PROP when
 the display spec is of the form `(space ...)'.
 (handle_display_spec): Return the value returned by
 handle_single_display_spec, not just 1 or zero.
 (handle_single_display_spec): If the display spec is of the form
 `(space ...)', and specifies display in the text area, return 2
 rather than 1.
 src/dispextern.h (struct bidi_it): Rename the disp_prop_p member
 into disp_prop; all users changed.
 src/bidi.c (bidi_fetch_char): If compute_display_string_pos returns
 DISP_PROP = 2, substitute the u+2029 PARAGRAPH SEPARATOR character
 for the text covered by the display property.
 lisp/buff-menu.el (Buffer-menu-buffer+size): Remove calls to
 bidi-string-mark-left-to-right; they are unnecessary now.
 doc/lispref/display.texi (Specified Space): Mention that `space' specs
 influence bidi reordering.
 (Bidirectional Display): Explain how to use `(space . PROPS)' for
 separating fields with bidirectional content.

2 files changed, 22 insertions, 2 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 4bf615328b..ca9c93b563 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,10 @@
+2011-08-25  Eli Zaretskii  <[email protected]>
+
+	* display.texi (Specified Space): Mention that `space' specs
+	influence bidi reordering.
+	(Bidirectional Display): Explain how to use `(space . PROPS)' for
+	separating fields with bidirectional content.
+
 2011-08-24  Eli Zaretskii  <[email protected]>
 
 	* display.texi (Bidirectional Display): Document return value in
diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 0593eba8f0..bf7cd126a2 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -3794,6 +3794,10 @@ with a @dfn{pixel ascent} specification (@pxref{Pixel Specification}).
 non-graphic terminals, but the other space properties in this section
 are not.
 
+  Note that space properties are treated as paragraph separators for
+the purposes of reordering bidirectional text for display.
+@xref{Bidirectional Display}, for the details.
+
 @node Pixel Specification
 @subsection Pixel Specification for Spaces
 @cindex spaces, pixel specification
@@ -6126,8 +6130,8 @@ with bidirectional content can be displayed @emph{to the left} of the
 preceding field, producing a jumbled display and messing up the
 expected layout.
 
-  To countermand this, you can use one of the following techniques for
-forcing correct order of fields on display:
+  To countermand this, we recommend that you use one of the following
+techniques for forcing correct order of fields on display:
 
 @itemize @minus
 @item
@@ -6146,6 +6150,15 @@ Include the tab character in the field separator.  The tab character
 plays the role of @dfn{segment separator} in the @acronym{UBA}
 reordering, whose effect is to make each field a separate segment, and
 thus reorder them separately.
+
+@cindex @code{space} display spec, and bidirectional text
+@item
+Separate fields with a @code{display} property or overlay with the
+property value of the form @code{(space . PROPS)} (@pxref{Specified
+Space}).  This display specification is treated by Emacs as a
+@dfn{paragraph separator}; the text before and after the separator is
+reordered separately, which avoids the influence of any field on its
+neighboring fields.
 @end itemize
 
 @defun bidi-string-mark-left-to-right string