Con una pequeña modificación entonces (tratá de entender cómo funciona):
Código PHP:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>test</title>
<style>
#container{
position:absolute;
left:274px;
top:72px;
}
#ventana_t {
position:relative;
width:216px;
visibility:;
height: 319px;
}
.barra_ventana {
background-color: #DDDDDD;
border: 1px solid #999999;
}
#prop_it {
background-color: #F8F8F8;
border: 1px solid #666666;
}
</style>
<script>
//inicio lib
function $(id){
return document.getElementById(id);
}
function addEvent(obj, evType, fn, useCapture){
if (obj.addEventListener){
obj.addEventListener(evType, fn, useCapture);
} else if (obj.attachEvent){
obj[fn+evType]=fn;
obj[fn+evType+'n']=function(){obj[fn+evType](window.event);}
obj.attachEvent("on"+evType, obj[fn+evType+'n']);
} else {
obj['on'+evType]=fn;
}
}
function removeEvent(obj, evType, fn, useCapture){
if (obj.removeEventListener){
obj.removeEventListener(evType, fn, useCapture);
} else if (obj.detachEvent){
obj.detachEvent("on"+evType, obj[fn+evType+'n']);
obj[fn+evType+'n']=null;
} else {
obj['on'+evType]=function(){};
}
}
function stopEvent(e) {
if (!e) e = window.event;
if (e.stopPropagation) {
e.stopPropagation();
} else {
e.cancelBubble = true;
}
}
function cancelEvent(e) {
if (!e) e = window.event;
if (e.preventDefault) {
e.preventDefault();
} else {
e.returnValue = false;
}
}
function getNextHighestDepth(){
var tCol=document.getElementsByTagName('*');
var z=0;
for(var i=0;i<tCol.length;i++){
if(tCol[i].style.zIndex>z){
z=tCol[i].style.zIndex;
}
}
return ++z;
}
//fin lib
arrastrable={};
function mover(e){
arrastrable.c2x=e.clientX;
arrastrable.c2y=e.clientY;
this.parentNode.parentNode.parentNode.style.left=arrastrable.c2x-arrastrable.c1x+arrastrable.o1x+'px';
this.parentNode.parentNode.parentNode.style.top=arrastrable.c2y-arrastrable.c1y+arrastrable.o1y+'px';
cancelEvent(e);
stopEvent(e);
}
function detener(){
removeEvent(this, 'mousemove', mover, false);
removeEvent(this, 'mouseup', detener, false);
}
function i(e){
if(this.parentNode.parentNode.parentNode.position!="relative"||!this.parentNode.parentNode.parentNode.style.position){
this.parentNode.parentNode.parentNode.style.position="relative";
this.parentNode.parentNode.parentNode.style.cssFloat="none";
this.parentNode.parentNode.parentNode.style.zIndex=getNextHighestDepth();
}
arrastrable.c1x=e.clientX;
arrastrable.c1y=e.clientY;
arrastrable.o1x=!isNaN(parseInt(this.parentNode.parentNode.parentNode.style.left))?parseInt(this.parentNode.parentNode.parentNode.style.left):0;
arrastrable.o1y=!isNaN(parseInt(this.parentNode.parentNode.parentNode.style.top))?parseInt(this.parentNode.parentNode.parentNode.style.top):0;
addEvent(this, 'mousemove',mover, false);
addEvent(this, 'mouseup',detener, false);
addEvent(this, 'mouseout',detener, false);
cancelEvent(e);
stopEvent(e);
}
function makeDraggable(){
for(var j=0;j<arguments.length;j++){
$(arguments[j]).style.cursor='move';
addEvent($(arguments[j]), 'mousedown',i, false);
}
}
function cerrar_VET(){
$('ventana_t').style.visibility="hidden";
}
window.onload=function(){
makeDraggable('esto');
}
</script>
</head>
<body>
<div id="container">
<div id="ventana_t">
<table border="0" cellpadding="0" cellspacing="0">
<!--DWLayoutTable-->
<tr id="esto">
<td height="11"><img src="Images/Ventana/derecha_ventana.gif" alt="-" width="10" height="30" /></td>
<td background="Images/Ventana/barra_ventana.gif"><span style="color: #FFFFFF; font-weight: bold; font-family:Arial, Helvetica, sans-serif;">Propiedades</span></td>
<td background="Images/Ventana/barra_ventana.gif"><a href="#" onClick="cerrar_VET();"><img src="Images/Ventana/cerrar_ventana.gif" alt="Clic para cerrar" width="100" height="25" border="0" /></a></td>
<td ><img src="Images/Ventana/izquierda_ventana.gif" alt="-" width="10" height="30" /></td>
</tr>
<tr class="barra_ventana">
<td colspan="4" valign="top" id="prop_it"><br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br /></td>
</tr>
</table></div></div>
</body>
</html>