Yo no le conseguí el error como tengo pocos conocimientos con el arrastre de objetos te daré esta dirección donde explican como arrastrar objetos
http://kusor.net/traducciones/brainjar.es/drag1.es.html
y ete pequeño ejemplo
Código HTML:
<HTML>
<HEAD>
</HEAD>
<style type="text/css">
.boxA {
background-color: #ffffc0;
border: 1px solid #000000;
padding: 8px;
position: relative;
left: 0px;
top: 0px;
width: 8em;
}
.boxB {
background-color: #fffff0;
border: 1px solid #000000;
padding: 2px;
}
</style>
<BODY>
<div style="z-index: 3; left: 4px; top: 0px;" class="boxA" onmousedown="dragStart(event)">Arrástrame</div>
</BODY>
</HTML>
<script type="text/javascript">
// Determine browser and version.
function Browser() {
var ua, s, i;
this.isIE = false;
this.isNS = false;
this.version = null;
ua = navigator.userAgent;
s = "MSIE";
if ((i = ua.indexOf(s)) >= 0) {
this.isIE = true;
this.version = parseFloat(ua.substr(i + s.length));
return;
}
s = "Netscape6/";
if ((i = ua.indexOf(s)) >= 0) {
this.isNS = true;
this.version = parseFloat(ua.substr(i + s.length));
return;
}
// Treat any other "Gecko" browser as NS 6.1.
s = "Gecko";
if ((i = ua.indexOf(s)) >= 0) {
this.isNS = true;
this.version = 6.1;
return;
}
}
var browser = new Browser();
// Global object to hold drag information.
var dragObj = new Object();
dragObj.zIndex = 0;
function dragStart(event, id) {
var el;
var x, y;
// If an element id was given, find it. Otherwise use the element being
// clicked on.
if (id){
dragObj.elNode = document.getElementById(id);
}else {
if (browser.isIE)
dragObj.elNode = window.event.srcElement;
if (browser.isNS)
dragObj.elNode = event.target;
// If this is a text node, use its parent element.
if (dragObj.elNode.nodeType == 3)
dragObj.elNode = dragObj.elNode.parentNode;
}
// Get cursor position with respect to the page.
if (browser.isIE) {
x = window.event.clientX + document.documentElement.scrollLeft
+ document.body.scrollLeft;
y = window.event.clientY + document.documentElement.scrollTop
+ document.body.scrollTop;
}
if (browser.isNS) {
x = event.clientX + window.scrollX;
y = event.clientY + window.scrollY;
}
// Save starting positions of cursor and element.
dragObj.cursorStartX = x;
dragObj.cursorStartY = y;
dragObj.elStartLeft = parseInt(dragObj.elNode.style.left, 10);
dragObj.elStartTop = parseInt(dragObj.elNode.style.top, 10);
if (isNaN(dragObj.elStartLeft)) dragObj.elStartLeft = 0;
if (isNaN(dragObj.elStartTop)) dragObj.elStartTop = 0;
// Update element's z-index.
dragObj.elNode.style.zIndex = ++dragObj.zIndex;
// Capture mousemove and mouseup events on the page.
if (browser.isIE) {
document.attachEvent("onmousemove", dragGo);
document.attachEvent("onmouseup", dragStop);
window.event.cancelBubble = true;
window.event.returnValue = false;
}
if (browser.isNS) {
document.addEventListener("mousemove", dragGo, true);
document.addEventListener("mouseup", dragStop, true);
event.preventDefault();
}
}
function dragGo(event) {
var x, y;
// Get cursor position with respect to the page.
if (browser.isIE) {
x = window.event.clientX + document.documentElement.scrollLeft
+ document.body.scrollLeft;
y = window.event.clientY + document.documentElement.scrollTop
+ document.body.scrollTop;
}
if (browser.isNS) {
x = event.clientX + window.scrollX;
y = event.clientY + window.scrollY;
}
// Move drag element by the same amount the cursor has moved.
dragObj.elNode.style.left = (dragObj.elStartLeft + x - dragObj.cursorStartX) + "px";
dragObj.elNode.style.top = (dragObj.elStartTop + y - dragObj.cursorStartY) + "px";
if (browser.isIE) {
window.event.cancelBubble = true;
window.event.returnValue = false;
}
if (browser.isNS)
event.preventDefault();
}
function dragStop(event) {
// Clear the drag element global.
dragObj.elNode = null;
// Stop capturing mousemove and mouseup events.
if (browser.isIE) {
document.detachEvent("onmousemove", dragGo);
document.detachEvent("onmouseup", dragStop);
}
if (browser.isNS) {
document.removeEventListener("mousemove", dragGo, true);
document.removeEventListener("mouseup", dragStop, true);
}
}
</script>