Subject: Re: Fix Mac OS X key bindings bug

From: Anders Lindgren <[email-masked]>
Date: Wed, 30 Dec 2015 09:50:23 +0100

Hi,

I'm looking into a key binding bug on OS X reported multiple times (19977,
21330, 21551). Two different patches have been submitted.

The original code looks like:

      if (is_left_key)
        {
          emacs_event->modifiers |= parse_solitary_modifier
            (ns_command_modifier);

          /* if super (default), take input manager's word so things like
             dvorak / qwerty layout work */
          if (EQ (ns_command_modifier, Qsuper)
              && !fnKeysym
              && [[theEvent characters] length] != 0)
            {
              /* XXX: the code we get will be unshifted, so if we have
                 a shift modifier, must convert ourselves */
              if (!(flags & NSShiftKeyMask))
                code = [[theEvent characters] characterAtIndex: 0];

One of the patches simply removes the `if (EQ(...))' statement. The other
modifies the code to strip away modifiers.

First question: What is the code in the `if (EQ(...))' supposed to do? In
other words, what will stop working if it is removed?

Second question: if it is needed for the LEFT command key, should the
corresponding code be added for the RIGHT?

I've tested removing the `if' and Emacs still seems to be working as
intended, both with a normal key layout and when Dvorak is used. If no one
comes up with a reason to keep the code, I will remove it.

Third question: Does anybody know of a good way to automatically test
things like this? What I'm looking for is a way to send keystrokes like
Cmd-Alt-a to Emacs, that way it could be possible to write tests ensuring
that things like this don't break in the future.

    -- Anders Lindgren