How do I enable accessibility alt-key shortcuts in GNOME window menus?

I'm using Ubuntu GNOME 16.04 with GNOME Shell 3.18.5.

I have just switched from XFCE to GNOME, and I am used to pressing Alt+Space and then C to close a window, Alt + Space and then X to maximize, etcetera. But in GNOME, I can't press those keys for those actions, because they aren't underlined:

and I have to scroll through with the arrow keys or click. Is there a way to enable those shortcuts?

I find that is easy to remap the GNOME shortcut to achieve the same thing, but mapping 3 keys is unsupported of you use the space key, it appears, so there are two options that I know:

The first is remapping the close window command; currently in “Ctrl + Q” or “Alt + F4” to “ Alt + C”. You can do this by going to Settings -> Devices -> Keyboard and then scrolling to the Close window command, then remapping the command, then again, you can only type two keys. Do the same to maximize window, to “Alt + X”

There is an extension for adding back those shortcuts https://extensions.gnome.org/extension/1695/menu-keyboard-shortcut/

<​rant>Gosh, GNOME is so annoying, they should have bi-monthly meetings about new ways to irritate users...<​/rant>