ext.net - How to use CausesValidation on an ext.net button?

Question

This question is about ext.net.

I hope to perform a form validation when the save button is clicked. In a regular ASP.NET webform, we usually use CausesValidation="true" ValidationGroup="gpSubmit" on the save button. But in an ext.net button, those two properties seems to be ineffective.

Any advice? How do you focus on the DOM control that fails the validation?

Here is my code.

<ext:Button ID="btnSave" runat="server" Text="Save" Icon="ApplicationEdit" 
    CausesValidation="true" ValidationGroup="gpSubmit">
    <DirectEvents>
        <Click 
            OnEvent="btnSave_Click" 
            Before="...;"
            Success="...;"
            Failure="...;">
            <EventMask ShowMask="true" Msg="Processing" />
            </Click>
    </DirectEvents>
</ext:Button>