var windowHandle = null;
var windowHandle_closed = false;

function launchwin(winurl,winfeatures) {
    windowHandle = window.open(winurl,'newwindow',winfeatures + ',scrollbars=yes,status=no');
    if (windowHandle_closed) {
        windowHandle_closed = false;
    }
}

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