function detectDocumentNavEnd(event) {
        if (event.keyCode === KeyEvent.DOM_VK_CONTROL) {  // Ctrl key
            MainViewManager.endTraversal();
            _addedNavKeyHandler = false;
            $(window.document.body).off("keyup", detectDocumentNavEnd);
        }
    }
When the Ctrl key is released, if we were in the middle of a next/prev document navigation
sequence, now is the time to end it and update the MRU order. If we allowed the order to update
on every next/prev increment, the 1st & 2nd entries would just switch places forever and we'd
never get further down the list.
@param {jQueryEvent} event Key-up event