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.

1 files changed, 21 insertions, 5 deletions

diff --git a/src/.gdbinit b/src/.gdbinit
index b3bb6b58267..73fecea5972 100644
--- a/src/.gdbinit
+++ b/src/.gdbinit
@@ -494,14 +494,30 @@ define pgx
   end
   # COMPOSITE_GLYPH
   if ($g->type == 1)
-    printf "COMP[%d (%d..%d)]", $g->u.cmp.id, $g->u.cmp.from, $g->u.cmp.to
+    printf "COMP[%d (%d..%d)]", $g->u.cmp.id, $g->slice.cmp.from, $g->slice.cmp.to
   end
-  # IMAGE_GLYPH
+  # GLYPHLESS_GLYPH
   if ($g->type == 2)
+    printf "GLYPHLESS["
+    if ($g->u.glyphless.method == 0)
+      printf "THIN]"
+    end
+    if ($g->u.glyphless.method == 1)
+      printf "EMPTY]"
+    end
+    if ($g->u.glyphless.method == 2)
+      printf "ACRO]"
+    end
+    if ($g->u.glyphless.method == 3)
+      printf "HEX]"
+    end
+  end
+  # IMAGE_GLYPH
+  if ($g->type == 3)
     printf "IMAGE[%d]", $g->u.img_id
   end
   # STRETCH_GLYPH
-  if ($g->type == 3)
+  if ($g->type == 4)
     printf "STRETCH[%d+%d]", $g->u.stretch.height, $g->u.stretch.ascent
   end
   xgettype ($g->object)
@@ -544,8 +560,8 @@ define pgx
   if ($g->right_box_line_p)
     printf " ]"
   end
-  if ($g->slice.x || $g->slice.y || $g->slice.width || $g->slice.height)
-    printf " slice=%d,%d,%d,%d" ,$g->slice.x, $g->slice.y, $g->slice.width, $g->slice.height
+  if ($g->slice.img.x || $g->slice.img.y || $g->slice.img.width || $g->slice.img.height)
+    printf " slice=%d,%d,%d,%d" ,$g->slice.img.x, $g->slice.img.y, $g->slice.img.width, $g->slice.img.height
   end
   printf "\n"
 end