Re: display bug for empty lines in recent git snapshot

[Giorgos Keramidas <keramida@ceid.upatras.gr>]

On Wed, 17 Nov 2010 10:31:08 +0100, Tassilo Horn <tassilo@member.fsf.org> wrote:
> Hi Giorgos,
>
> I've already filed this as bug#7417.

The change that introduced this bug in my local mirror of the git trunk
is one committed by Eli on Nov 13:

: changeset:   111519:3355ca38548d
: user:        Eli Zaretskii <eliz@gnu.org>
: date:        Sat Nov 13 15:29:31 2010 +0200
: files:       doc/emacs/ChangeLog doc/emacs/display.texi doc/emacs/mule.texi
:              doc/emacs/rmail.texi doc/lispref/ChangeLog
:              doc/lispref/display.texi etc/ChangeLog etc/NEWS lisp/ChangeLog
:              lisp/international/characters.el src/.gdbinit src/ChangeLog
:              src/dispextern.h src/term.c src/w32term.c src/xdisp.c src/xterm.c
: description:
: 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.

I think there's some exception we have to add here for newline
characters, because they are treated as GLYPHLESS_DISPLAY_THIN_SPACE or
as GLYPHLESS_DISPLAY_EMPTY_BOX with a width of 1 space, but I am not
sure what the best way to do this would be.  Maybe Eli has a good idea
of how this can be fixed?