//dropdown_initialize.js
       var preloaded = [];

       for (var i = 1; i <= 8; i++) {
        preloaded[i] = [loadImage(i + "-1.gif"), loadImage(i + "-1.gif")];       //设置图片的OnMouseOver和OnMouseOut的路径
       }

       function initz() {

        if (mtDropDown.isSupported()) {
         mtDropDown.initialize();
        }
       }

       function loadImage(sFilename) {
        var img = new Image();
        img.src ="" + sFilename;
        return img;
       }

       function swapImage(imgName, sFilename) {
        document.images[imgName].src = sFilename;
       }