RE: Keyboard Behaviors for Elements with Role "Grid"

>However, it's entirely possible that Ctrl+Tab may already be taken by the
>OS or the browser.  In that case, perhaps the square bracket keys, ] and [,
>could be used to denote forward and backward motion, and be used to
>navigate among editable cells.
Yes indeed Control+tab is used for navigating between multiple tabs open in
the browser. 
I did not catch how left/right bracket keys will substitute arrow keys
because of unavailability of control+tab.
Using left/right bracket keys is not so intuitive  and their position on the
keyboard too is not as accessible as arrow keys.
Sailesh Panchang
Accessibility Services Manager (Web and Software)
Deque Systems Inc. (www.deque.com)
11130 Sunrise Valley Drive, Suite #140,
Reston VA 20191
Phone: 703-225-0380 (ext 105)
E-mail: sailesh.panchang@deque.com