>>>>> On Wed, 27 Oct 2010 23:56:47 +0900, Keitaro Miyazaki <keitaro.miyazaki@gmail.com> said:

> Yes, NSString counts length of string as number of Unicode characters,
> and I suppose range is counted in a similar way.

>      "... The length method returns the total number of Unicode
> characters in the string ..."

>        NSString Class Reference
>        <http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/Reference/NSString.html>

In this context, "number of Unicode characters" should be read as
"number of `unichar' values", where the type `unichar' is of 16-bit
width.  Actually, it is confusing.

Also, selected range handling is not enough for the following case:

  (activate Kotoeri) a i u e o left left left

The first screenshot is for the NS port with your patch, and the
second one is for my Mac port
(http://lists.gnu.org/archive/html/emacs-devel/2010-09/msg01439.html).

				     YAMAMOTO Mitsuharu
				mituharu@math.s.chiba-u.ac.jp