var CouponWindow = null;

function CouponWindowOpen(sHref)
{
    if (CouponWindow != null && CouponWindow.closed) {
        CouponWindow = null;
    }

    var wndWidth  = 700;
    var wndHeight = 330;

    if (CouponWindow) {
        CouponWindow.focus();
        return true;
    }

    var leftPos = (screen.width  - wndWidth) / 2;
    var topPos  = (screen.height - wndHeight) / 2 - 20;
    var features = 'toolbar=no, location=no, directories=no, menubar=no, scrollbars=no, resizable=no, status=no, width=' + wndWidth + ', height=' + wndHeight + ', top=' + topPos + ',left=' + leftPos;

    CouponWindow = window.open(sHref, null, features);
    CouponWindow.focus();

    return true;
}