function getTopWin ()
{
    var windowManager = Components. classes ['@mozilla.org/appshell/window-mediator;1']. getService();
    var windowManagerInterface = windowManager.
                                 QueryInterface (Components. interfaces. nsIWindowMediator);
    var topWindowOfType = windowManagerInterface. getMostRecentWindow ("navigator:browser");
    
    if (topWindowOfType)
    {
        return topWindowOfType;
    }
    return null;
}
function setBookmark ()
{
    netscape. security. PrivilegeManager. enablePrivilege ("UniversalXPConnect");
    var w = getTopWin ();
    var b = w. getBrowser ();
    w. addBookmarkAs (b, false, false);
}