function isKeypressCommand(nativeEvent) {
	  return (nativeEvent.ctrlKey || nativeEvent.altKey || nativeEvent.metaKey) &&
	  // ctrlKey && altKey is equivalent to AltGr, and is not a command.
	  !(nativeEvent.ctrlKey && nativeEvent.altKey);
	}
Return whether a native keypress event is assumed to be a command.
This is required because Firefox fires `keypress` events for key commands
(cut, copy, select-all, etc.) even though no character is inserted.