I have a grid, a selectionModel (checkbox) and a store with approximately 30000 records. Then I want to select and unselect all records from C # since when doing it from the web browser collapses.

In other words I require a method similar to:
App.grdGeocercasAll.getSelectionModel (). DeselectAll ();
But done from the server with code in C #.
Try the following but it does not work:
RowSelectionModel sm = grid.SelectionModel.Primary as RowSelectionModel;
Sm.DeselectAll ();
Sm.UpdateSelection ();
Thanks for your help