Anonymous

<backgrounds>
    <statetype name="backgroundstates">
        <state name="normal">
            <imagetype name="normal_button">
                <filename>shared/text_button_off.png</filename>
            </imagetype>
        </state>
        <state name="selected">
            <imagetype name="normal_button">
                <filename>shared/text_button_on.png</filename>
            </imagetype>
        </state>
    </statetype>
</backgrounds>

OR

<regular-background filename="shared/text_button_off.png" />
<selected-background filename="shared/text_button_on.png" />