bug#21260: 23.2; Devanagari windows 10

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 21260@debbugs.gnu.org
> From: Jim Funderburk <funderburk1@verizon.net>
> Date: Sun, 16 Aug 2015 16:21:44 -0400
> 
>   Please refer to this dropbox link for images: 
> https://www.dropbox.com/s/dqxe4edz5d4nmnc/emacs-gdi.zip?dl=0
>    1. Opening with gdi is a move in the right direction.

Actually, no, not in the direction you need to enjoy the correct
display of Devanagari.  The GDI font back-end is unable to display
scripts that need complex shaping and ligation, and Devanagari
requires those features.

I asked you to try GDI to confirm my suspicion that something is wrong
with Uniscribe, the main font back-end we use on Windows.  Now the
suspicion is confirmed.

>       The result is shown in 'open_with_gdi.png' -  the Devanagari renders
>    2. Not all is exactly right, however.  Notice the highlighted part of 
> other image (open-with_gdi_prob.png)
>        When I moved the mouse and clicked on a character in the last 
> line,  the rendering of the character changed
>         Obviously, it should not do this.  [This happens elsewhere, on 
> most, but not all characters.]

This is expected with the GDI back-end.