Widget computeTabGroup() {
		ToolItem[] items = _getItems();
		if (tabItemList == null) {
			int i = 0;
			while (i < items.length && items[i].control == null)
				i++;
			if (i == items.length)
				return super.computeTabGroup();
		}
		int index = 0;
		while (index < items.length) {
			if (items[index].hasFocus())
				break;
			index++;
		}
		while (index >= 0) {
			ToolItem item = items[index];
			if (item.isTabGroup())
				return item;
			index--;
		}
		return super.computeTabGroup();
	}