Start drag operation

i've created in my apllication an drag&drop event on a listview. The drag&drop works but i have a little problem when i open a file from this listview by double cliking the item.
.When i double click the item from listview that opens a file it will automatically starts the drag&drop operation too. How can i modify the code below to accept only when i press the mouse button and move the mouse pointer

procedure TForm1.ViewUrlMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
   if (Button = mbLeft) then
   with Sender as TListView do
     begin
    if ViewUrl.GetItemAt(X,Y)<>Nil then
     begin
        if Button=mbRight then exit;
        BeginDrag(false);
     end;
     end;
end;Start Free Trial