​The bugged behavior is that `ns-use-native-fullscreen' set to nil is not read
when launching emacs.


The attached patch should fix this. The problem is that when the frame is
made, the current value of ns-use-native-fullscreen is copied to a variable
and that's only reset when the frame goes from fullscreen to windowed. I
believe the original intent was to ensure that the mode could not change
while the window was fullscreen already.

This resets the value of fs_is_native if the frame is not already
fullscreen, which allows it to respect the value at the time of the first
fullscreen.

Without this, the only way to get the behavior that Sean is expecting is to
set ns-use-native-fullscreen in early-init, which should not be necessary.