function moveFocus(dir, elements) {
			var idx = -1, navigationRoot = getNavigationRoot();

			elements = elements || getFocusElements(navigationRoot.getEl());

			for (var i = 0; i < elements.length; i++) {
				if (elements[i] === focusedElement) {
					idx = i;
				}
			}

			idx += dir;
			navigationRoot.lastAriaIndex = moveFocusToIndex(idx, elements);
		}
Moves the focus forwards or backwards.

@private
@param {Number} dir Direction to move in positive means forward, negative means backwards.
@param {Array} elements Optional array of elements to move within defaults to the current navigation roots elements.