case KeyEvent.DOM_VK_UP:
            step = event.shiftKey ? step * STEP_MULTIPLIER : step;
            yOffset = Number($.trim(this.$selectionBase[0].style.bottom.replace("%", "")));
            adjustedOffset = (event.keyCode === KeyEvent.DOM_VK_DOWN) ? (yOffset - step) : (yOffset + step);
            yOffset = Math.min(100, Math.max(0, adjustedOffset));