hi,
here my solution:
first do you make your popup by the editor
then rename the file uploads/smp_popup.html in something else .php
into the new file .php you have to insert the next code in the head section to grab the url in the parent frame:
<script type="text/javascript">
function myurl()
{
var parentUrl = parent.location.href;
return parentUrl;
}
</script>
then insert in the place you want the link to close the popup (in this case is a image link):
<script type="text/javascript">
document.write("<a href=" + myurl() + " target=\"_top\"><img title=\"Enter into the website\" src=\"/wp-content/uploads/2011/07/enter_website.png\" alt=\"Enter into the website\" width=\"225\" height=\"80\" /></a>")
</script>
at last, you have to insert the complete url in the admin panel, to load the new page.php instead of the default html page.
ciao
marco