Edit: Finally I found out what the problem was: The name of the Popup has to be different from "popup".
<script language="javascript">debug_window = openWithSelfMain("http://192.168.1.3/project/misc.php?action=showpopups&type=debug&file=dummy_1150221738.html", "popup", 680, 450);</script>
<html>
<head><title></title>
<script type="text/javascript" src="http://www.myurl.de/include/xoops.js"></script>
<script type="text/javascript">
</script>
</head>
<body onload=setInterval('self.location.reload()',10000)>
</body>
</html>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=windows-1252"></HEAD>
<BODY></BODY></HTML>
<?php
include "../../mainfile.php";
global $xoopsDB, $xoopsConfig, $xoopsModule, $HTTP_SERVER_VAR;
$online_handler =& xoops_gethandler('online');
if (is_object($xoopsUser)) {
$uid = $xoopsUser->getVar('uid');
$uname = $xoopsUser->getVar('uname');
} else {
$uid = 0;
$uname = '';
}
if (is_object($xoopsModule)) {
$online_handler->write($uid, $uname, time(), $xoopsModule->getVar('mid'), $HTTP_SERVER_VARS['REMOTE_ADDR']);
} else {
$online_handler->write($uid, $uname, time(), 0, $HTTP_SERVER_VARS['REMOTE_ADDR']);
}
if (!$xoopsUser) exit();
$uid = $xoopsUser->getVar('uid');
$result = $xoopsDB->query("SELECT msg_id, from_userid, msg_time FROM ".$xoopsDB->prefix("priv_msgs")." WHERE to_userid=".$uid." AND read_msg=0");
?>
<html>