resolving idle time after accidentally cancelling prompt

[Adam Spiers <orgmode@adamspiers.org>]

Hi there,

The `org-clock-idle-time' feature is really fantastic.  However I
occasionally miss the [(kK)eep (sS)ubtract (C)ancel] prompt in the
minibuffer and press another key which cancels it; then I have to run
org-resolve-clocks manually.  I can imagine a scenario where I
mistakenly thought that the window manager focus was in another
window, started typing, accidentally cancelled the prompt, and never
even noticed it was there in the first place - resulting in a
permanently dangling clock.  Would it be worth making this code
idiot-proof ...

    (if (or (null ch)
	    (not (memq ch '(?k ?K ?s ?S ?C))))
	(message "")

.. so that the only way to cancel the prompt is to press `C' ?  It
would also be nice if upon cancellation it did

  (message "Use `M-x org-resolve-clocks' to resolve dangling clocks at any time.")

Thanks,
Adam