bug#42915: 27.1; Setting ns-function-modifier to control breaks control for certain keys

[Alan Third]

On Tue, Aug 18, 2020 at 10:22:18AM -0400, Ryan C. Thompson wrote:
> On a mac, run:
> 
> emacs -Q --eval "(setq ns-function-modifier 'control)"
> 
> Then try C-right, C-home, and similar key combinations. Emacs will act as if
> control is not being held down, i.e. C-right will run right-char instead of
> right-word. Indeed, C-h k C-right shows the key binding for right, not
> C-right. However, other key combinations, such as C-f, work as expected.
> 
> As far as I can tell, this only started happening after I updated to Emacs
> 27. I was previously using this config with Emacs 26.3 and never saw this
> issue. So I believe this is a new bug in Emacs 27.

Can you please try the attached patch?

Note that there may be some change to how "function" keys, like return
and the arrow keys, are handled when using the fn key. I can't
remember exactly how they worked with Emacs 26, but I believe the new
behaviour should be more consistent across the board.
-- 
Alan Third

0001-Handle-fn-functions-keys-better-on-NS-bug-42915.patch
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