text: jQuery.md=function(opt){
   var modalObj=opt.modal;
   var timeout=opt.time;
   var url=opt.url;
   var zIndex=99;
   var thW,thH;
  
   bheight = function(){
    if ($.browser.msie && $.browser.version < 7) {
      var scrollHeight = Math.max(
  	  document.documentElement.scrollHeight,
  	  document.body.scrollHeight
      );
      var offsetHeight = Math.max(
  	  document.documentElement.offsetHeight,
  	  document.body.offsetHeight
      );
  
      if (scrollHeight < offsetHeight) {
  	  return $(window).height();
      } else {
  	  return scrollHeight;
      }
    } else {
      return $(document).height();
    }
  }
   bwidth = function() {
     if ($.browser.msie && $.browser.version < 7) {
       var scrollWidth = Math.max(
  	 document.documentElement.scrollWidth,
  	 document.body.scrollWidth
     );
     var offsetWidth = Math.max(
  	 document.documentElement.offsetWidth,
  	 document.body.offsetWidth
     );
  
     if (scrollWidth < offsetWidth) {
  	 return $(window).width();
     } else {
  	return scrollWidth;
     }
    } else {
      return $(document).width();
    }
  }
   $(modalObj).css({display:"block","z-index":zIndex + 1});
   if($("#grey_div").html()==null) $("<div id='grey_div'></div>").appendTo("body").css({height: bheight ,width: bwidth,"z-index":zIndex }).bgiframe();
    if(url!=undefined){
  	$(modalObj).text("正在加载...");
  	thW=150;
  	thH=30;
  	$(modalObj).css({top : w()[0] , left : w()[1] });
  //	$(window).resize(bg);
  //	$(window).scroll(bg);
  	$(modalObj).load(url,function(){
  	    thW=$(modalObj).width();
  	    thH=$(modalObj).height();
  		g();
       }); 
   }
   else{
  	thW=$(modalObj).width();
  	thH=$(modalObj).height();
  	g();
   }
   function g(){	
      $(modalObj).css({top : w()[0] , left : w()[1] });
  	$(".grey_close").live("click",closeGrey);
  	$(window).resize(bg); 
  	$(window).scroll(bg);
  	if(timeout!=undefined) hideGrey();
   }
   
   function w(){
  	var st=document.documentElement.scrollTop;//滚动条距顶部的距离
  	var sl=document.documentElement.scrollLeft;//滚动条距左边的距离
  	var ch=document.documentElement.clientHeight;//屏幕的高度
  	var cw=document.documentElement.clientWidth;//屏幕的宽度
  	var objT=Number(st)+(Number(ch)-Number(thH))/2;
  	var objL=Number(sl)+(Number(cw)-Number(thW))/2;
  	return [objT,objL];
   }
   function bg(){
  	 $("#grey_div").css({height: bheight ,width: bwidth });
  	 $(modalObj).css({top : w()[0] , left : w()[1] });
   }
   function closeGrey(){
  	$(modalObj).css("display", "none");
  	$("#grey_div").remove();
   }
   function hideGrey(){
  	$(modalObj).fadeOut(timeout,function(){
  	  $("#grey_div").remove();
  	});
   }
  }
  