实现 http://topic.csdn.net/u/20120515/11/c8cc4c5b-5750-46c7-93bf-b41cb26d12e8.html?07571103379596025
实现 http://www.gzsums.edu.cn/webclass/html/marquee.html
手册 http://www.phpx.com/man/dhtmlcn/objects/MARQUEE.html