Paging toolbar: select first row

Hi!

The following method selects the first row of a grid by click a refresh button.

Works well.

Code:

onRefresh: function(grid, selected, record, eOpts){
    var grid = Ext.ComponentQuery.query('#gridtemId')[0];
    var store = grid.getStore();
    grid.getSelectionModel().select(0);
}

What was intended that when change page in the paging toolbar (1 -> 2) was selected the first line of the grid of the new page (this selection fire an event in my app).

How can I do this?

Thanks in advance.

Paging toolbar: select first row