var windowHandle = null;
var windowHandle_closed = false;

function openWindow(url,width,height) {
    windowHandle = window.open(url,'image','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=no,width=' + width + ',height=' + height);
    if (windowHandle_closed) {
        windowHandle_closed = false;
    }
}

function closeWindow() {
    if (windowHandle != null) {
        if (!windowHandle_closed) {
            windowHandle_closed = true;
            windowHandle.close();
        }
    }
}