bug#19977: 24.4; Incorrect translation of Super modifier with Ctrl or Meta on OS X

[Adrian Robert <adrian.b.robert@gmail.com>]

On 2016.3.29, at 20:44, Philipp Stephani <p.stephani2@gmail.com> wrote:

> 
> 
> Adrian Robert <adrian.b.robert@gmail.com> schrieb am Di., 29. März 2016 um 19:19 Uhr:
> 
> On 2016.3.29, at 19:57, Eli Zaretskii <eliz@gnu.org> wrote:
> 
> >> From: Philipp Stephani <p.stephani2@gmail.com>
> >> Date: Tue, 29 Mar 2016 16:38:52 +0000
> >> Cc: 19977@debbugs.gnu.org
> >>
> >> If I comment out the if block below the comment
> >>
> >> /* if super (default), take input manager's word so things like
> >> dvorak / qwerty layout work */
> >>
> >> in nsterm.m, everything works. Unless somebody can explain why that if block exists at all (i.e. why
> >> [theEvent characters] instead of [theEvent charactersIgnoringModifiers] is used), then I'd suggest to
> >> remove the block completely.
> >>
> >> Attached a patch to remove this code.
> >
> > Adrian, any comments?  It's your code from 7 years ago.
> 
> 
> Heh, well of the top of my head… ;-)
> 
> Did you try testing Dvorak / Qwerty layout?  If not, that’s under System Preferences, Keyboard, add new, English, select Dvorak or Dvorak / Qwerty.
> 
> From what I remember, the issue had to do with cmd-key shortcuts when one of those layouts was in use.  I think users were expecting the letter reported for the cmd shortcut to either agree with or disagree with the dvorak layout.  Using [theEvent characters] caused it to use what they were expecting.
> 
> It sounds like either this wasn’t the right solution, or user expectations vary.  In either case I would agree with simplifying the code and removing the part you suggest.
> 
> 
> Yes, I can see what the problem is, thanks for the pointer. Basically in a couple of layouts (there are others, e.g. "Gujarati - QUERTY"), Command acts as shift-like character, like Option and Shift, selecting a different character, and not as a control-like character. For Option, Emacs allows switching between shift-like and control-like behavior using the `ns-alternate-modifier' option. The same should be implemented for Command.
> However, the code for `ns-alternate-modifier' is also somewhat broken. If it's set to 'none, C-M-<letter> doesn't work any more. This needs a bit more thought. What exactly is supposed to happen if both a shift-like and a control-like modifier are pressed at the same time? Emacs is inconsistent here: C-S-a remains C-S-a, but M-S-a gets translated to M-A.


I would say the correct behavior is to combine the modifier and the “shift”ed result.  C-S-a should be C-A.  But my memory is fuzzy as to whether nsterm should do this or it happens in emacs generic code.  And if ns-alternate-modifier is ‘none’, then there is no such thing as C-M-letter, just C-letter, where the identify of ‘letter' is determined by what comes from opt-<original-key>.