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

[Xue Fuqiao]

On Thu, Sep 5, 2013 at 10:33 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>> Date: Thu, 5 Sep 2013 22:08:21 +0800
>> From: Xue Fuqiao <xfq.free@gmail.com>
>>
>>   emacs -Q
>>   !                      ;; input an exclamation mark (#x21)
>>   C-x 8 RET 2 0 E 4 RET  ;; COMBINING ENCLOSING UPWARD POINTING TRIANGLE
>>   RET                    ;; Newline
>>   C-x 8 RET 2 6 A 0 RET      ;; WARNING SIGN
>>
>> I tried many fonts, but all results look weird (the first line is
>> incomplete and too large).
>
> What font(s) were used to display this character?

Menlo, Times New Roman, Courier New, FreeMono, FreeSans, and FreeSerif.

> If you go to the first line, which shows the character only partially,
> and type C-a, does that fix the problem?

No.

> What about "M-x redraw-display RET"?

Nothing changes.

> Finally, if you go to the first partially displayed character and type
> "C-u C-x =", what does Emacs show?

Similar to Jan's.  The general-category for this character is "Me (Mark,
Enclosing)", so it is a nonspacing mark, which is a kind of combining
character.

See:
http://www.unicode.org/glossary/#enclosing_mark
http://www.unicode.org/glossary/#nonspacing_mark
http://www.unicode.org/glossary/#combining_character

-- 
Best regards, Xue Fuqiao.
http://www.gnu.org/software/emacs/