When file a bug report (see below for feature requests)

What version of GoTTY are you using (gotty --version)?

gotty version v1.4.0

What operating system and browser are you using?

macOS Monterey 12.5
Google Chrome (Desktop) Version 103.0.5060.134 (Official Build) (x86_64)
Safari (Desktop) Version 15.6 (17613.3.9.1.5)
Safari (iPadOS 15.5)

What did you do?

I run spacemacs via gotty with
gotty --port 11111 --permit-write --reconnect emacsclient --tty -a ""
when I go to localhost:11111 I can successfully use emacs.
Since when I press the "option" key I want instead to send a "meta" key, I have tried using this config (and restarting gotty)

preferences {                                                                   
    alt_is_meta = true
}

or this config

preferences {                                                                   
    alt_is_meta = true
    alt_is_what = "browser-key"
}

but nothing changes.

What did you expect to see?

I would expect the meta key to be sent. For example, if I press for instance Option-x, I expect emacs in the browser to recognize M-x.

What did you see instead?

I get the option key instead. In the example above, if I press Option-x I get the character ≈. So I can't use most of the emacs keybinding. As a workaround I can use spacemacs and switch to evil-mode, but I would like to use the default emacs keybindings.