private void MenuItem_Checked(object sender, RoutedEventArgs e)
        {
            MenuItem menuItem = sender as MenuItem;
            MenuItem item     = menuItem.Parent as MenuItem;

            //foreach (var i in item)
            //{
            //    if ()
            //    {

            //    }
            //}
            if ((string)menuItem.Header == "ירושלים")
            {
                UnitsViewList.ItemsSource = from Group in bl.GetGroupHostingUnitsByArea()
                                            where Group.Key == Areas.ירושלים
                                            select Group into g
                                            from GR in g

                                            select GR;
            }
            if ((string)menuItem.Header == "צפון")
            {
                UnitsViewList.ItemsSource = from Group in bl.GetGroupHostingUnitsByArea()
                                            where Group.Key == Areas.צפון
                                            select Group into g
                                            from GR in g

                                            select GR;
            }
            if ((string)menuItem.Header == "דרום")
            {
                UnitsViewList.ItemsSource = from Group in bl.GetGroupHostingUnitsByArea()
                                            where Group.Key == Areas.דרום
                                            select Group into g
                                            from GR in g

                                            select GR;
            }
            if ((string)menuItem.Header == "מרכז")
            {
                UnitsViewList.ItemsSource = from Group in bl.GetGroupHostingUnitsByArea()
                                            where Group.Key == Areas.מרכז
                                            select Group into g
                                            from GR in g

                                            select GR;
            }
            if ((string)menuItem.Header == "הכל")
            {
                UnitsViewList.ItemsSource = bl.GetAllHostingUnits().ToList();
            }
        }