模擬ListBox按上下鍵會有游標移動的功能

目前尚有問題：未能得知第一個被選的

    case TWMKey(Msg).CharCode of
      VK_DELETE : BtnRealTimeDelete.Click;

      VK_DOWN :
      begin
        if (LBRealTime.ItemIndex = LBRealTime.Count-1) or (LBRealTime.Count=0) then
          exit;
        LBRealTime.ItemIndex := LBRealTime.ItemIndex+1;
        if GetKeyState(VK_SHIFT) >= 0  then  //代表沒按shift
        begin
          for i:=0 to LBRealTime.Count-1 do
            LBRealTime.Selected [i] := false;
          g_RealTimeShift := false;
          LBRealTime.Selected[LBRealTime.ItemIndex] := true;
        end else
        begin
          for i:=0 to LBRealTime.Count-1 do
            LBRealTime.Selected [i] := false;
          g_RealTimeShift := true;
          if g_RealTimeShiftRec<= LBRealTime.ItemIndex then
            for i:=g_RealTimeShiftRec to LBRealTime.ItemIndex do
              LBRealTime.Selected [i] := true
          else
            for i:=g_RealTimeShiftRec downto LBRealTime.ItemIndex do
              LBRealTime.Selected [i] := true;
        end;
        LBRealTimeClick(self);
      end;
      VK_UP :
      begin
        if (LBRealTime.ItemIndex = 0) or (LBRealTime.Count=0) then
          exit;
        LBRealTime.ItemIndex := LBRealTime.ItemIndex-1;
        if GetKeyState(VK_SHIFT) >= 0  then  //代表沒按shift
        begin
          for i:=0 to LBRealTime.Count-1 do
            LBRealTime.Selected [i] := false;
          g_RealTimeShift := false;
          LBRealTime.Selected[LBRealTime.ItemIndex] := true;
        end else
        begin
          for i:=0 to LBRealTime.Count-1 do
            LBRealTime.Selected [i] := false;
          g_RealTimeShift := true;
          if g_RealTimeShiftRec<= LBRealTime.ItemIndex then
            for i:=g_RealTimeShiftRec to LBRealTime.ItemIndex do
              LBRealTime.Selected [i] := true
          else
            for i:=g_RealTimeShiftRec downto LBRealTime.ItemIndex do
              LBRealTime.Selected [i] := true;
        end;
        LBRealTimeClick(self);
      end;

    end;