网页中对象的拖动

<table width="100" border=1 onselectstart="return false" style="position:absolute;left:50;top:150" >
<tr>
    <td bgcolor="#cccccc" align="center" style="cursor:move" onmousedown="MouseDown(this)" onmousemove="MouseMove()" onmouseup="MouseUp()">title1</td>
</tr>
<tr>
    <td align="center" height="60">content</td>
</tr>
</table>
<script>
var Obj;
var oMove;
function MouseDown(obj){
Obj=obj;
oMove=Obj.parentElement.parentElement.parentElement;
Obj.setCapture();
Obj.l=event.x-oMove.style.pixelLeft;
Obj.t=event.y-oMove.style.pixelTop;
}
function MouseMove(){
if(Obj!=null){
    oMove.style.left = event.x-Obj.l;
    oMove.style.top = event.y-Obj.t;
    }
}
function MouseUp(){
if(Obj!=null){
    Obj.releaseCapture();
    Obj=null;
    }
}
</script>