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

["Jan Djärv" <jan.h.d@swipnet.se>]

Hello.

5 sep 2013 kl. 19:56 skrev Eli Zaretskii <eliz@gnu.org>:

>> From: Jan Djärv <jan.h.d@swipnet.se>
>> Date: Thu, 5 Sep 2013 19:33:04 +0200
>> Cc: xfq.free@gmail.com,
>> 15273@debbugs.gnu.org
>> 
>> Hello.
>> 
>> 5 sep 2013 kl. 19:24 skrev Eli Zaretskii <eliz@gnu.org>:
>> 
>>> On one OSX system, the result of "! C-x 8 RET 2 0 E 4 RET" _looks_
>>> like a single character, but actually isn't: I can move cursor twice
>>> across the result, and "C-u C-x =" doesn't show the composition
>>> results.  Is that what you see?
>> 
>> Yes.
> 
> Thanks.  So this is not a composition at all, and the wicked way the
> triangle is displayed is not Emacs's fault at all.  I guess the font
> used by NS or the font driver are at fault here.  FWIW, on MS-Windows,
> I see the ! and the triangle after it correctly, as 2 separate
> characters (using Code2000 font).

What do you mean by composition?  Is it that the two characters are replaced by another character that is equivalent?  That may not be possible since we can combine any character with the triangle, such a glyph may not be available.  Or is it simply that Emacs treats the two characters as one?
Why is displaying the ! and the triangle after it as separate characters correct?  The triangle is a composing character and should be displayed above the !.

	Jan D.