When you click link, a sub-window is indicated.

Click on this.

Source Code

[ Main Window ]

<html>
<head>
<script language="JavaScript">
    function NNCheck(version) {
        if((navigator.appName.indexOf('Netscape') >= 0)
        && (version <= parseInt(navigator.appVersion.substring(0, 3)))) {
            return true;
        } else {
            return false;
        }
    }

    function openWin(url) {
        return false;
    }
</script>
<script language="JavaScript1.1">
    var w = window;

    function openWin(url) {
        if ((w == window) || w.closed) {
            w = open(url, "_blank", "resizable=yes,scrollbars=yes,width=400,height=100");
        } else {
            if(w.location.href.indexOf(url) < 0) {
                w.location.href = url;
            }
            w.focus();
        }
        return(false);
    }

    function closeWin() {
        if((w != window) && !w.closed) {
            w.close();
        }
    }
</script>
</head>

<body onunload="closeWin()">
<script TYPE="text/javascript">
    document.write('<p>When you click link, a sub-window is indicated.<\/p>');
    document.write('<p><a href="sub2-e.html" onclick="return openWin(\'sub2-e.html\')">Click on this.<\/a><\/p>');
</script>
</body>
</html>

[ Sub Window ]

<html>
<head>
<title>Sub-window.</title>
<script language="JavaScript">
    function changeWin(url) {
        return false;
    }
</script>
<script language="JavaScript1.1">
    function changeWin(url) {
        opener.focus();
        opener.location.href = url;
        return(false);
    }
</script>
</head>
<body bgcolor="#ffffff" text="#000000">
<p>This is a sub-window.</p>
<p>When you click link, a parent window changes.</p>
<p><a href="index-e.html" onclick="return changeWin('index-e.html')">Click on this.</a></p>
</body>
</html>