Unbind C-RET in emacs?

Question

My finger tends to linger on the Ctrl key and I happen to hit C-RET quite often. I also use cua-mode which binds this to cua-clear-rectangle-mark. I don't want C-RET bound to anything while in this mode.

I can't seem to unbind it though. I've tried:

(global-unset-key (kbd "C-RET"))
(global-unset-key (kbd "<C-return>"))
(global-unset-key [(control return)])
(define-key global-map (kbd "C-RET") 'ignore)
(define-key global-map (kbd "<C-return>") 'ignore)
(define-key global-map [(control return)] 'ignore)

I also tried the following in my .inputrc with no success:

"\C-RET": "\n"

There also doesn't seem to be a cua-mode-map:

;; Doesn't work
(define-key cua-mode-map "C-RET" nil)

Answer 1

In Emacs 25, if you run C-h k C-RET it will tell you that C-RET is bound in cua-global-keymap, so that's where we unset it

(define-key cua-global-keymap [C-return] nil)

It seems to be set in the same keymap in 24.4 as well.