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, 16 insertions, 0 deletions

diff --git a/etc/ChangeLog b/etc/ChangeLog
index a01fb8beef2..06bd63e9f8c 100644
--- a/etc/ChangeLog
+++ b/etc/ChangeLog
@@ -1,3 +1,7 @@
+2010-11-13  Eli Zaretskii  <eliz@gnu.org>
+
+        * NEWS: Document display of glyphless characters.
+
 2010-11-11  Eric Schulte  <schulte.eric@gmail.com>
 
         * refcards/orgcard.tex: Add new Babel key sequences.
diff --git a/etc/NEWS b/etc/NEWS
index 7deaaf92fd3..9d8b126588a 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -138,6 +138,18 @@ with Xft.  To change font, use X resource faceName, for example:
 Emacs.pane.menubar.faceName:  Courier-12
 Set faceName to none and use font to use the old X fonts.
 
++++
+** Enhanced support for characters that have no glyphs in available fonts
+If a character has no glyphs in any of the available fonts, Emacs by
+default will display it either as a hexadecimal code in a box or as a
+thin 1-pixel space.  In addition to these two methods, Emacs can
+display these characters as empty box, as an acronym, or not display
+them at all.  To change how these characters are displayed, customize
+the variable `glyphless-char-display-control'.
+
+On character terminals these methods are used for characters that
+cannot be encoded by the `terminal-coding-system'.
+
 ** On graphical displays, the mode-line no longer ends in dashes.
 
 ** Basic SELinux support has been added.