Create a HTML file that will include your site (the pop-up window) and in between the HEAD tags insert the following code:
PHP Code:
<script language="JavaScript">
<!--
function popup(theURL,winname,features) {
window.open(theURL,winname,features);
}
//-->
</script>
Modify, if needed...
Then in your main HTML file (the one that should be remained open) place the following code in the BODY tag:
Code:
onLoad="popup('http://www.yourdomain.com/yourfile.html','YourWinName', 'toolbar=no, location=no,
status=no, menubar=no, scrollbars=no, resizable=no, width=800, height=600')";
Modify the details to your liking.