How to add SelectionChange as a listener for in aspx

Question

I need to add a selectionchange for column in aspx

<ext:Column ID="Column8" Text="<%$ Resources: name %>" DataIndex="ID"
Sortable="true" MenuDisabled="true" Align="Center" Width="220px" runat="server">
     <Editor>
            <ext:ComboBox ID="ComboBox1" runat="server" StoreID="st1" DisplayField="myname" ValueField="ID" Width="200" Editable="false" AllowBlank="false">
            </ext:ComboBox>
      </Editor>
  <Renderer Fn="mynameRenderer" />
</ext:Column>

Trying to add listener to my above logic which is not getting recognized as valid html

<Listeners>                                                        
    <SelectionChange Handler="App.hdnname.setValue(selected[0].data.ID);" />
 </Listeners>