ASPxGridViewCustomCallbackEventArgs Class

protected void Grid_CustomCallback(object sender, ASPxGridViewCustomCallbackEventArgs e) {
     if(e.Parameters == "ApplyCustomFilter")
          Grid.FilterExpression = "City = 'Bratislava'";
     if(e.Parameters == "ApplyCustomGrouping") { 
          Grid.DataColumns["City"].GroupBy();
          Grid.ExpandAll();
     }
}

Protected Sub Grid_CustomCallback(ByVal sender As Object, ByVal e As ASPxGridViewCustomCallbackEventArgs)
     If e.Parameters = "ApplyCustomFilter" Then
          Grid.FilterExpression = "City = 'Bratislava'"
     End If
     If e.Parameters = "ApplyCustomGrouping" Then
          Grid.DataColumns("City").GroupBy()
          Grid.ExpandAll()
     End If
End Sub

<script type="text/javascript">
     function onApplyFilterButtonClick(s, e) {
          grid.PerformCallback("ApplyCustomFilter");
     }
     function onApplyGroupingButtonClick(s, e) {
          grid.PerformCallback("ApplyCustomGrouping");
     }
</script>
…

<dx:ASPxGridView ID="Grid" runat="server" KeyFieldName="ID" ClientInstanceName="grid" OnCustomCallback="Grid_CustomCallback">
     <Columns>
          <dx:GridViewDataColumn FieldName="ID" />
          <dx:GridViewDataColumn FieldName="FirstName" />
          <dx:GridViewDataColumn FieldName="LastName" />
          <dx:GridViewDataColumn FieldName="City" />
     </Columns>
</dx:ASPxGridView>

<dx:ASPxButton ID="ApplyFilterButton" runat="server" AutoPostBack="false" UseSubmitBehavior="false" Text="Apply Custom Filter">
     <ClientSideEvents Click="onApplyFilterButtonClick" />
</dx:ASPxButton>

<dx:ASPxButton ID="ApplyGroupingButton" runat="server" AutoPostBack="false" UseSubmitBehavior="false" Text="Apply Custom Grouping">
     <ClientSideEvents Click="onApplyGroupingButtonClick" />
</dx:ASPxButton>