Custom function call on CTRL/CMD + S using CKEditor 4

I have a custom ajax function, save(), that I call on my form when I press CTRL/CMD + S:

document.addEventListener("keydown", function(e) {
  if (e.keyCode == 83 && (navigator.platform.match("Mac") ? e.metaKey : e.ctrlKey)) {
    e.preventDefault();   
    save();
  }
}, false);

I'm using CKEditor 4 for my textarea field:

CKEDITOR.replace('content',{ height: '250px' });

If the focus isn't on the CKEditor textarea, pressing CTRL/CMD + S calls the save() function triggered from the "keydown" listener.

However, if focus is on the CKEditor textarea, pressing CTRL/CMD + S calls my browser "Save Page As" dialog (note: I'm on Chrome FWIW).

How can I make sure that the save() function is executed even when focus is on the CKEditor textarea?

Any help would be most appreciated.

Thanks,

Bardi