Fix and document display of glyphless characters.

 src/xdisp.c (set_cursor_from_row): Fix cursor positioning on
 zero-width characters.
 (syms_of_xdisp) <glyphless-char-display>: Doc fix.
 src/.gdbinit (pgx): Adapt to latest changes in `struct glyph'.
 src/w32term.c (x_draw_glyphless_glyph_string_foreground): Draw the
 box before drawing the glyphs inside it.
 src/dispextern.h (enum glyphless_display_method): Rename
 GLYPHLESS_DISPLAY_HEXA_CODE to GLYPHLESS_DISPLAY_HEX_CODE.  All
 users changed.
 src/term.c (append_glyphless_glyph, produce_glyphless_glyph): Fix
 comments.
 (produce_glyphless_glyph): Enclose "U+nnnn" and "empty box"
 whitespace in "[]", to simulate a box.  Don't use uninitialized
 variable `width'.
 lisp/international/characters.el (glyphless-char-display-control):
 Renamed from glyphless-char-control; all users changed.  Doc fix.
 Signal an error if display method is not one of the recognized
 symbols.
 doc/emacs/rmail.texi (Rmail Coding): Characters with no fonts are not
 necessarily displayed as empty boxes.
 doc/emacs/mule.texi (Language Environments, Fontsets): Characters with no
 fonts are not necessarily displayed as empty boxes.
 doc/emacs/display.texi (Text Display): Document display of glyphless
 characters.
 doc/lispref/display.texi (Usual Display): Characters with no fonts are not
 necessarily displayed as empty boxes.
 etc/NEWS: Document display of glyphless characters.

2 files changed, 8 insertions, 3 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 5607d179aad..d6853e0066d 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,8 @@
+2010-11-13  Eli Zaretskii  <eliz@gnu.org>
+
+        * display.texi (Usual Display): Characters with no fonts are not
+        necessarily displayed as empty boxes.
+
 2010-10-31  Glenn Morris  <rgm@gnu.org>
 
         * maps.texi (Standard Keymaps): Update File menu description.
diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 92f96d302d9..6e872ad4233 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -5579,9 +5579,9 @@ digit characters representing the character code in octal.  (A display
 table can specify a glyph to use instead of @samp{\}.)
 
 @item
-Multibyte character codes above 256 are displayed as themselves, or as a
-question mark or empty box if the terminal cannot display that
-character.
+Multibyte character codes above 256 are displayed as themselves, or as
+a question mark or a hex code or an empty box if the terminal cannot
+display that character.
 @end itemize
 
   The usual display conventions apply even when there is a display