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

[tsuucat]

>> 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. 

--
tsuucat