dragndrop插件的代码, 看不明白, 高手请指点

下面是dragndrop插件的代码, 在IE6(FF正常)下测试, 没有设置html标签样式position和top时出现bug,

           当点击要拖动的层时, 它会先跑到窗口坐标(0,0)处 , 问题出在那里呢? 顺便翻译一下代码最好-_-!!

复制代码 //(function($) {     $.extend($.fn, {         getCss: function(key) {             var v = parseInt(this.css(key));             if (isNaN(v))                 return false;             return v;         }     });     $.fn.Drags = function(opts) {    //定义了一个方法, 叫Drags         var ps = $.extend({          //对参数扩展             zIndex: 20,             opacity: .7,             handler: null,             onMove: function() { },             onDrop: function() { }         }, opts);         var dragndrop = {            //方法里的方法, 里面又有两个方法drag, 和drop             drag: function(e) {                 var dragData = e.data.dragData;  //dragData是传进来的参数                 dragData.target.css({                     left: dragData.left + e.pageX - dragData.offLeft,                     top: dragData.top + e.pageY - dragData.offTop                 });                 dragData.handler.css({ cursor: 'move' });                 dragData.onMove(e);             },             drop: function(e) {                 var dragData = e.data.dragData;                 dragData.target.css(dragData.oldCss); //.css({ 'opacity': '' });                 dragData.handler.css('cursor', dragData.oldCss.cursor);                 dragData.onDrop(e);                 $().unbind('mousemove', dragndrop.drag)                     .unbind('mouseup', dragndrop.drop);             }         }                  //遍历执行, 并返回         return this.each(function() {             var me = this;             var handler = null;             if (typeof ps.handler == 'undefined' || ps.handler == null)                 handler = $(me);             else                 handler = (typeof ps.handler == 'string' ? $(ps.handler, this) : ps.handle);             handler.bind('mousedown', { e: me }, function(s) {                 var target = $(s.data.e);                 var oldCss = {};                 if (target.css('position') != 'absolute') {                     try {                         target.position(oldCss);                     } catch (ex) { }                     target.css('position', 'absolute');                 }                 oldCss.cursor = target.css('cursor') || 'default';                 oldCss.opacity = target.getCss('opacity') || 1;                 var dragData = {                                               //初始数据                     left: oldCss.left || target.getCss('left') || 0,                     top: oldCss.top || target.getCss('top') || 0,                     width: target.width() || target.getCss('width'),                     height: target.height() || target.getCss('height'),                     offLeft: s.pageX,                     offTop: s.pageY,                     oldCss: oldCss,                     onMove: ps.onMove,                     onDrop: ps.onDrop,                     handler: handler,                     target: target                 }                 target.css('opacity', ps.opacity);                 $().bind('mousemove', { dragData: dragData }, dragndrop.drag)  //事件, 对象属性, 对象方法                     .bind('mouseup', { dragData: dragData }, dragndrop.drop);             });         });     } //})(jQuery);

ok 自己搞定了

// top: oldCss.top || target.getCss('top') || 0,
top: $(this).offset().top;