Delphi下DBGrid拖放问题

DBGrid的拖放问题：设为dmAutomatic，则点击无法移动记录，设为dmManual则在记录上点击时无法响应MouseDown事件，请问哪位大侠能解决
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这是我在网上找的代码，经测试非常不错：

procedure TForm1.DBGrid1MouseMove(Sender: TObject; Shift: TShiftState; X, 
   Y: Integer); 
begin 
   if ssLeft in Shift then 
     TDBGrid(Sender).BeginDrag(False); 
end; 

procedure TForm1.TreeView1DragOver(Sender, Source: TObject; X, Y: Integer; 
   State: TDragState; var Accept: Boolean); 
begin 
   Accept := Source is TDBGrid; 
end; 

procedure TForm1.TreeView1DragDrop(Sender, Source: TObject; X, Y: Integer); 
var 
   AnItem: TTreeNode; 
   I: Integer; 
   S: String; 
begin 
   with Sender as TTreeView do 
   begin 
     AnItem := GetNodeAt(X, Y); 
     with Source as TDBGrid do 
     begin 
       S := ''; 
       for I := 0 to Columns.Count - 1 do 
         S := S + Columns[I].Field.AsString + ' '; 
     end; 
     Items.AddChild(AnItem, S); 
     AnItem.Expand(True); 
   end; 
end;