protected void add2collection()
        {
            lock (cisco_objects)
            {
                cisco_objects.Add(this);
            }
            CiscoObjectsWindow.AddToTable(this);
            Activate();

            forget_old();
        }
        static internal void RestoreLastDeleted()
        {
            CiscoObject n;

            lock (cisco_objects)
            {
                n = cisco_objects.Where(x => x.Deleted).OrderByDescending(x => x.DeleteTime).FirstOrDefault();
                if (n == null)
                {
                    CiscoObjectsWindow.EnableRestore(false);
                    return;
                }
            }
            n.DeleteTime = DateTime.MinValue;
            CiscoObjectsWindow.AddToTable(n);
            CiscoObjectsWindow.EnableRestore(cisco_objects.Where(x => x.Deleted).Count() > 0);
        }