★★像这种对候选的元素复制拖拽怎么实现？？？

Question

function moveObj(moveObj,ctrlObj){
if(moveObj.style.position!="absolute")moveObj.position="absolute";
ctrlObj._onmousedown=ctrlObj.onmousedown;
ctrlObj.onmousedown=function(){
var mt=event.srcElement;
if(mt._onmousedown)mt._onmousedown();
if(!mt.moveObj||event.button!=1)return;
with(document.body){
document.body.moveObj=mt.moveObj;
document.body.oldX=event.clientX+scrollLeft;
document.body.oldY=event.clientY+scrollTop;
document.body._onmousemove=onmousemove;
document.body._onmouseup=onmouseup;
}
document.body.onmousemove=function(){
try{
with(document.body){
if(!moveObj)return;
var sl=scrollLeft,st=scrollTop;
var newX=event.clientX+sl,newY=event.clientY+st;
moveObj.style.left=moveObj.style.pixelLeft+newX-oldX;
moveObj.style.top=moveObj.style.pixelTop+newY-oldY;
oldX=event.clientX+sl;
oldY=event.clientY+st;
}
}catch(e){};
}
document.body.onmouseup=function(){
document.releaseCapture();
with(document.body){
if(!moveObj)return;
onmouseup=_onmouseup;onmousemove=_onmousemove;
if(moveObj.style.pixelTop<=0)moveObj.style.top=0;
if(moveObj.style.pixelLeft<=0)moveObj.style.left=0;
}

}
document.body.setCapture();
}
ctrlObj.moveObj=moveObj;
}