var windowHandle = null;
var windowHandle_closed = false;

function newWindow(theURL,winName,features) {
  windowHandle = window.open(theURL,winName,features);
    if (windowHandle.closed) {
        windowHandle_closed = false;
    }
}

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