什么原因导致'M-S-t'(meta + shift + t)键绑定不被占用?

What causes `M-S-t` (meta + shift + t) key binding not to take?

By default, C-S-t and M-S-t are both unbound in my Emacs. Hence, when I press them, they are translated into C-t and M-t. Fine, but I want to use them for a tweak on the original function, and therefore put these lines in my .emacs:

(global-set-key (kbd "C-S-t") 'transpose-chars-backward)
(global-set-key (kbd "M-S-t") 'transpose-words-backward)

The functions there are my own, and work fine when called via M-x.

This works for C-S-t, but not for M-S-t which still gets translated to M-t. The message on C-h k M-S-t confirms this.

It's not that it's impossible to configure M-S- combinations in general, because M-q and M-S-q do different things.

What causes this inconsistency and how can I get around it?

I'm running Aquamacs on Mac OS X 10.9.5.

Here you have two different ways to do what you want:

(global-set-key (kbd "M-T") 'transpose-words-backwards)
(global-set-key [(meta shift t)] 'transpose-words-backwards)

I am not sure what causes the (kbd "M-S-t") working differently from (kbd "C-S-t"), btw. Time ago I became an adept to vector notation ([(meta shift t)]) as I find it more predictable (I always get it right the first time, and with kbd notation sometimes I needed a couple of tries).

C-h k M-S-t gives "M-t (translated from M-T) ...". In my experience, C-h k always tells you exactly what to give kbd.
@jpkotta I take it your experience of Aquamacs is limited. ;) what I got was “⌥T (translated from ⌥⇧T)”. I'm not going to explore whether I could actually use that as kbd arguments.
@njlarsson You're right, I've never used Aquamacs. That sounds like a bug though; you should report it.