<html>
<head>
<script>
    window.onload = function()
    {
        if (window.testRunner)
            testRunner.globalFlag = true;
    } 

    var windowURL = '';
    var openedWindow;
    function openWindow()
    {
        openedWindow = window.open(windowURL);
    }
</script>
</head>
<body>
<button onclick="openWindow()">Open Window</button>
</body>
</html>