bug#4143: OS/X drag and drop bug report

["A. Boveia" <boveia@hep.uchicago.edu>]

In earlier versions (e.g. 22.x), the Mac OS/X Emacs.app correctly  
implemented drag and drop for the file icon in the frame title bar.  
For example, while visiting a file "file.txt", I could drag this icon  
into a Finder window and the file would be copied there, or I could  
drag the icon into an email message and the file would be attached.

In this version (23.1.2), the drag does not always pick up the visited  
file---instead it sometimes picks up the file corresponding to some  
other buffer.



> In GNU Emacs 23.1.2 (i386-apple-darwin9.7.0, NS apple-appkit-949.46)
>  of 2009-08-01 on fluxion.local
> Windowing system distributor `Apple', version 10.3.949
> configured using `configure  '--with-ns' '--with-jpeg=no' '--with- 
> gif=no' '--with-tiff=no''
>
> Important settings:
>   value of $LC_ALL: nil
>   value of $LC_COLLATE: nil
>   value of $LC_CTYPE: nil
>   value of $LC_MESSAGES: nil
>   value of $LC_MONETARY: nil
>   value of $LC_NUMERIC: nil
>   value of $LC_TIME: nil
>   value of $LANG: nil
>   value of $XMODIFIERS: nil
>   locale-coding-system: nil
>   default-enable-multibyte-characters: t
>
> Major mode: C++/l
>
> Minor modes in effect:
>   diff-auto-refine-mode: t
>   desktop-save-mode: t
>   show-paren-mode: t
>   tooltip-mode: t
>   mouse-wheel-mode: t
>   menu-bar-mode: t
>   file-name-shadow-mode: t
>   global-font-lock-mode: t
>   font-lock-mode: t
>   global-auto-composition-mode: t
>   auto-composition-mode: t
>   auto-encryption-mode: t
>   auto-compression-mode: t
>   size-indication-mode: t
>   column-number-mode: t
>   line-number-mode: t
>   transient-mark-mode: t
>   abbrev-mode: t
>