实现主界面的折叠菜单，视图表现为左边的菜单，可以查看主菜单下的子菜单。主菜单上下滑动。-Folding menu for the main interface, view performance for the left menu, you can view the sub-menu under the main menu. Slide up and down the main menu.

flex中accordion组件的应用,实现折叠效果,flex基础,仅供参考-the flex accordion component applications folding effect, flex foundation, for reference only