//Êó±êÍ϶¯µØͼÂþÓÎ
var dragapproved=false;
var x=y=0;

function move()
 {
    if(event.button==1 && dragapproved){
      var sx=event.clientX-x;
	  var sy=event.clientY-y;
      x=event.clientX;
      y=event.clientY;	  
	  self.scrollBy(-sx,-sy);
    }
    return false
 }
function drags()
{
 if(event.button!=1) return
 dragapproved=true;
 x=event.clientX;
 y=event.clientY;
 document.onmousemove=move;
}

document.onmousedown=drags;