// JavaScript Document
$(function() {    
    $(".hmain").hover(function() {   
        $(this).children("ul").slideDown();   
        changeIcon($(this).children("a"));   
    }, function() {   
        $(this).children("ul").slideUp();   
         changeIcon($(this).children("a"));   
    });   
});   
//指示图标的展打开和关闭   
function changeIcon(mainNode) {   
    if (mainNode) {   
        if (mainNode.css("background-image").indexOf("closed.gif") >= 0) {   
            mainNode.css("background-image", "url(img/open.gif)");   
        } else {   
            mainNode.css("background-image", "url(img/closed.gif)");   
        }   
  
    }   
}