No you cannot create a popup without a titlebar but you can make a sudo popup that has no titlebar.
try something like this:
<html>
<head>
<title>title</title>
<style>
table.PopUp {
width: 300px;
height: 400px;
border-collapse: border-collapse;
border: 2px solid #000000;
background-color: #ffffff;
}
table.PopUp td {
border: 1px solid #000000;
}
#colorPalette {
position: absolute;
}
</style>
<script>
function getElement(aID){
var rv = (document.getElementById) ? document.getElementById(aID) :
document.all[aID];
return rv;
}
function togglePopUp() {
e = getElement('PopUp');
e.style.visibility = e.style.visibility=='hidden'?'':'hidden';
}
</script>
</head>
<body>
<div id="PopUp" style="visibility: hidden;">
<table class='PopUp' cellpadding=0 cellspacing=1>
<tr>
<td height="100%" width="100%">Your Popup Content</td>
</tr>
</table>
</div>
<a href="#" OnClick="togglePopUp()">Open/Close Popup</a>
</body>
</html>