<div id='pop-editor' style='width: 520px;height:430px;border:1px solid red;position: absolute;left:100px;top:200px;' onmousedown='down(event)' onmouseup='up()'>asdfdsf</div>

var posX;
var posY;
var popDiv;
var dragable;

function down(e){
    popDiv = document.getElementById("pop-editor");
    e = e || window.event; //如果是IE
    posX = e.clientX - parseInt(popDiv.style.left);
    posY = e.clientY - parseInt(popDiv.style.top);
    dragable = true;
    document.onmousemove = move;
}

function move(ev){
    if(dragable == true){
        ev = ev || window.event;//如果是IE
        popDiv.style.left = (ev.clientX - posX) + "px";
        popDiv.style.top = (ev.clientY - posY) + "px";
    }
}

function up(){
    dragable = false;
}