bug#15273: 24.3.50; Combining character sequences are displayed weirdly

[Eli Zaretskii]

> From: Kenichi Handa <handa@gnu.org>
> Cc: jan.h.d@swipnet.se, xfq.free@gmail.com, 15273@debbugs.gnu.org
> Date: Tue, 10 Sep 2013 22:58:20 +0900
> 
> In article <834n9vl5q1.fsf@gnu.org>, Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Next, I'm not sure whether Emacs composes them correctly if
> >> the underlying font driver doesn't support OTF's "mark" and
> >> "mkmk" features.  The function compose-gstring-for-graphic
> >> has a code for such a case, but I don't remember that I
> >> wrote a code for "enclosing combining marks".
> 
> > Looks like Uniscribe should need this, at least on XP: I do get a
> > composition, but the left part of the triangle is off-screen.
> 
> I saw the same rendering on GNU/Linux with a font
> which doesn't have a proper feature for U+20E4.

Then I guess it's something related to the fact that the base
character '!' is much narrower than the triangle.

> I'm now investigating how to improve compose-gstring-for-graphic.

Thank you.