bug#44641: [PATCH] Ignore modifiers when processing WM_IME_CHAR messages

[Eli Zaretskii]

> From: tsuucat <tsuucat@icloud.com>
> Date: Mon, 16 Nov 2020 12:07:26 +0900
> Cc: 44641@debbugs.gnu.org
> 
> 
> >> Current Emacs for Windows recognizes modifier keys even when inputting
> >> with IME. Some IMEs use modifier keys to input characters, so this
> >> causes inconvenient for such IME users.
> > 
> > You say "some IMEs", so I wonder whether ignoring modifier keys for
> > WM_IME_CHAR is always the right thing.  Do you know for sure? is that
> > documented somewhere?  (I'm not an expert on MS-Windows IMEs.)
> 
> I believe this change will not affect other IME users. Other IME users
> simply don't use modifier keys to input multibyte characters. For
> example, Chinese IME users type Space to select and input the
> candidate, but typing Ctrl+Space doesn't mean users select and input
> the candidate (= WM_IME_CHAR messages will not happen). 
> 
> Some Japanese IME users type Ctrl+m or Ctrl+n to select and input the
> candidate and they want to send Ctrl to IME not to Emacs.
> 
> I don't have just the right documentation but this change just follows
> the way X build Emacs does. 

OK, thanks.  I installed your changes on the emacs-27 branch, but I
also added a variable, w32-ignore-modifiers-on-IME-input, that allows
to get back the old behavior, in case the new behavior adversely
effects some use cases.

With that, I'm closing this bug report.