Add a mechanism to fix the current viewport (scrollbar position) when new items are inserted. Currently, when you insert items before the viewport's start, the scrollbar position is offset.

To work this around set the GroupRenderMode property of RadGridView to Flat.

When GroupRenderMode is set to Nested the issue can be overcome by calling the BringIntoView method on the row returned in the ScrollIntoViewAsync method's callback:  
gridView.ScrollIndexIntoViewAsync(index,
  new Action<FrameworkElement>((f) =>
  {
      f.BringIntoView();
  }));

Placing text in quotes after exclude search operator and search getting the wrong result. As a workaround to get the desired result the search string can be changed in this way: from  -"Rio de" to  -Rio + -de.