Raise or downgrade the selected listview item

# Region increase position
       /// <Summary>
       /// Raise Method
       /// </Summary>
       /// <Param name = "listview"> </param>
       Private void listviewupmove (listview)
       {
           If (listview. selecteditems. Count = 0)
           {
               Return;
           }

           If (listview. selecteditems [0]. index> 0)
           {
               Foreach (listviewitem LVI in listview. selecteditems)
               {
                   Listviewitem lviselecteditem = LVI;
                   Int indexselecteditem = LVI. index;
                   // Listview. Items. removeat (indexselecteditem );
                   // Listview. Items. insert (indexselecteditem-1, lviselecteditem );
                   Listview. items [indexselecteditem]. Selected = false;
                   Listview. items [indexselecteditem-1]. Selected = true;

                   Listview. items [indexselecteditem-1]. ensurevisible (); // the scroll bar is automatically rolled up.
               }
           }
       }
       # Endregion
       # Region lowering position
       /// <Summary>
       /// Lowering Method
       /// </Summary>
       /// <Param name = "listview"> </param>
       Private void listviewdownmove (listview)
       {
           If (listview. selecteditems. Count = 0)
           {
               Return;
           }

           If (listview. selecteditems [0]. index <listview. Items. Count-1)
           {
               Foreach (listviewitem LVI in listview. selecteditems)
               {
                   Listviewitem lviselecteditem = LVI;
                   Int indexselecteditem = LVI. index;
                   Listview. items [indexselecteditem]. Selected = false;
                   Listview. items [indexselecteditem + 1]. Selected = true;

                   Listview. items [indexselecteditem+ 1]. ensurevisible (); // the scroll bar is automatically rolled down.
               }
           }
       }
       # Endregion