public void DeleteTabById(int id)
        {
            Tab tab = (from Tab t in Tabs
                       where t.Id == id
                       select t).Single();
            Group group = tab.Group;

            Tabs.DeleteOnSubmit(tab);
            if (group.Tabs.Count <= 1)
            {
                Groups.DeleteOnSubmit(group);
            }

            SubmitChanges();
        }