title: how to keep the visible content after nstableview reloaddata?
body: <p>I have a subclassed nstableview whose data source array may increase, by calling reloadData: I can refresh to reflect the data updating.</p>
  
  <p>But after reloadData:, the tableview will always scroll to the new cell with the same old row number (for example, if the tableview was showing the 2nd cell, after reloadData:, the tableview will scroll to the new 2nd cell, therefore, the visible content of the tableview will change). How can I disable this automatic behavior and keep the visible content unchanged after the updating?</p>
  
  <p>thanks in advance!</p>